Urmimala Chatterjee - Academia.edu (original) (raw)

Papers by Urmimala Chatterjee

Research paper thumbnail of Spidroin N-terminal domain forms amyloid-like fibril based hydrogels and provides a protein immobilization platform

Nature Communications

Recombinant spider silk proteins (spidroins) have multiple potential applications in development ... more Recombinant spider silk proteins (spidroins) have multiple potential applications in development of novel biomaterials, but their multimodal and aggregation-prone nature have complicated production and straightforward applications. Here, we report that recombinant miniature spidroins, and importantly also the N-terminal domain (NT) on its own, rapidly form self-supporting and transparent hydrogels at 37 °C. The gelation is caused by NT α-helix to β-sheet conversion and formation of amyloid-like fibrils, and fusion proteins composed of NT and green fluorescent protein or purine nucleoside phosphorylase form hydrogels with intact functions of the fusion moieties. Our findings demonstrate that recombinant NT and fusion proteins give high expression yields and bestow attractive properties to hydrogels, e.g., transparency, cross-linker free gelation and straightforward immobilization of active proteins at high density.

Research paper thumbnail of Nutritional Implications of Algal Polysaccharides

Research paper thumbnail of Advances in early diagnosis of hepatocellular carcinoma

Hepatoma Research, 2019

Hepatocellular carcinoma (HCC) is the most recurrent hepatic malignancy and the third in the canc... more Hepatocellular carcinoma (HCC) is the most recurrent hepatic malignancy and the third in the cancer-related casualties in the west. The frequently-documented causes of HCC are chronic liver infections by hepatitis B virus or hepatitis C virus, nonalcoholic fatty liver disease, cirrhosis, exposure to aflatoxins and tobacco smocking, etc. Clinical presentation of this fatal disease ranges from asymptomatic to upper abdominal pain or common health conditions like weight loss or lethargy. Among current surveillance strategy for suspected patients, liver imaging and serum alpha fetoprotein estimation has been regularly recommended. However, sensitivity of this diagnostic methodology especially in early detections, often suffers from compromised sensitivity and selectivity. Various image based and serological biomarkers for HCC has been introduced in recent decades with varied sensitivity as stand-alone or combined diagnostic protocol. The current article will review the status of HCC diagnosis with respect to common diagnostic protocol, and upcoming novel biomarkers.

Research paper thumbnail of Assessment of Altered Fucosylation of Serum α-1-Acid Glycoprotein in Hepatocellular Carcinoma Patients by Gold-Nanoparticle Aggregation Immunoassay

Material Science Research India, 2018

Gold nanoparticles have attracted considerable attention due to their unique properties and poten... more Gold nanoparticles have attracted considerable attention due to their unique properties and potential applications as optical probes. When proteins that are adsorbed on gold nanoparticles subsequently get cross-linked by any interaction specific to that protein, the size of the aggregates increases and this enhancement of size have been used for sensitive, convenient and powerful tool to monitor the presence of the specific cross-linkers. Dynamic light scattering (DLS) is a technique that is routinely used for detecting aggregation in macromolecular solutions. In this work, we first applied DLS to identify specific glycoprotein–lectin interactions exclusively present in the serum of hepatocellular carcinoma patients compared to healthy controls that showed the altered fucosylation of a serum protein, Serum α-1-Acid glycoprotein. Further, based on the DLS data a simple, rapid, serological assay was developed based on antibody coated gold nanoparticle and fucose binding lectin (Aleuri...

Research paper thumbnail of Biological activity of marine sponge lectins

Marine Glycobiology, 2016

Research paper thumbnail of Gold nanoparticle-based novel visual diagnostic method for the detection of specific IgE to test for food allergies

Analytical Methods, 2016

Visual test for food allergy by GNP-based plasmonic detection of specific IgE in sera.

Research paper thumbnail of Effects of Congo red on aβ(1-40) fibril formation process and morphology

ACS chemical neuroscience, Jan 21, 2010

Alzheimer's disease (AD), an age-related neurodegenerative disorder, is the most common form ... more Alzheimer's disease (AD), an age-related neurodegenerative disorder, is the most common form of dementia, and the seventh-leading cause of death in the United States. Current treatments offer only symptomatic relief; thus, there is a great need for new treatments with disease-modifying potential. One pathological hallmark of AD is so-called senile plaques, mainly made up of β-sheet-rich assemblies of 40- or 42-residue amyloid β-peptides (Aβ). Hence, inhibition of Aβ aggregation is actively explored as an option to prevent or treat AD. Congo red (CR) has been widely used as a model antiamyloid agent to prevent Aβ aggregation. Herein, we report detailed morphological studies on the effect of CR as an antiamyloid agent, by circular dichroism spectroscopy, photo-induced cross-linking reactions, and atomic force microscopy. We also demonstrate the effect of CR on a preaggregated sample of Aβ(1-40). Our result suggests that Aβ(1-40) follows a different path for aggregation in the pres...

Research paper thumbnail of Poly-N-methylated Amyloid β-Peptide (Aβ) C-Terminal Fragments Reduce Aβ Toxicity in Vitro and in Drosophila melanogaster

Journal of Medicinal Chemistry, 2009

Alzheimer&amp... more Alzheimer's disease (AD), an age related neurodegenerative disorder, threatens to become a major health-economic problem. Assembly of 40- or 42-residue amyloid beta-peptides (Abeta) into neurotoxic oligo-/polymeric beta-sheet structures is an important pathogenic feature in AD, thus, inhibition of this process has been explored to prevent or treat AD. The C-terminal part plays an important role in Abeta aggregation, but most Abeta aggregation inhibitors have targeted the central region around residues 16-23. Herein, we synthesized hexapeptides with varying extents of N-methylation based on residues 32-37 of Abeta, to target its C-terminal region. We measured the peptides' abilities to retard beta-sheet and fibril formation of Abeta and to reduce Abeta neurotoxicity. A penta-N-methylated peptide was more efficient than peptides with 0, 2, or 3 N-methyl groups. This penta-N-methylated peptide moreover increased life span and locomotor activity in Drosophila melanogaster flies overexpressing human Abeta(1-42).

Research paper thumbnail of In vitro ADMET and physicochemical investigations of poly-N-methylated peptides designed to inhibit Aβ aggregation

Bioorganic & Medicinal Chemistry, 2010

N-Methylation is a common strategy for improving oral bioavailability of peptide-based lead struc... more N-Methylation is a common strategy for improving oral bioavailability of peptide-based lead structures. Herein, we present a detailed study on how the degree of N-methylation affects the absorption-distribution-metabolism-excretion-toxicity (ADMET) properties such as solubility, membrane transport, proteolytic stability, and general cell toxicity of the investigated peptides. As representative structures we chose hexapeptides 1-8. These peptides, corresponding to N-methylated analogues of residues 16-21 and 32-37 of the Abeta-peptide, pathological hallmark of Alzheimer's disease (AD), have previously been shown to inhibit aggregation of Abeta fibrils in vitro. This study suggests that poly-N-methylated peptides are non-toxic and have enhanced proteolytic stability over their non-methylated analogues. Furthermore, solubility in aqueous solution is seen to increase with increased degree of N-methylation, while membrane transport was found to be low for all investigated hexapeptides. The present results, together with those reported in the literature, suggest that poly-N-methylated peptides, especially shorter or equal to six residues, can be suitable candidates for drug design.

Research paper thumbnail of Effects of Congo Red on A� 1-40 Fibril Formation Process and Morphology

Acs Chemical Neuroscience, 2010

Research paper thumbnail of Chitosan as a Universal Drug Delivery Vehicle

Encyclopedia of Marine Biotechnology, 2020

Research paper thumbnail of Role of pepsin in modifying the allergenicity of bhetki (Lates calcarifer) and mackerel (Rastrelliger kanagurta) fish

Indian journal of biochemistry & biophysics, 2007

The effect of pepsin digestion on the allergenicity of raw and thermally processed (boiled and fr... more The effect of pepsin digestion on the allergenicity of raw and thermally processed (boiled and fried) fish muscle extracts of two widely consumed fishes bhetki (Lates calcarifer) and mackerel (Rastrelliger kanagurta) was studied. Sere were collected from 110 patients who were hypersensitive to fish, as evidenced by their clinical history, symptoms and positive skin-prick test results. The various extracts after digestion with pepsin at different times of incubation were tested for specific IgE-binding activity by ELISA and immunoblotting with patients' sera. All the extracts of both the fishes retained their allergenicity as evidenced by ELISA and immunoblotting. In bhetki, maximum allergenicity was found in the pepsin-digested fried extract, whereas similar treatment decreased the allergenicity in fried mackerel. Results showed that raw as well as thermally processed allergens of both the fishes maintained strong allergenicity, even after digestion with pepsin for different tim...

Research paper thumbnail of Identification of allergens in Indian fishes: hilsa and pomfret exemplified by ELISA and immunoblotting

Indian journal of experimental biology, 2005

Enzymed-linked immunosorbent assay of hilsa and pomfret muscle extracts showed specific IgE bindi... more Enzymed-linked immunosorbent assay of hilsa and pomfret muscle extracts showed specific IgE binding to ten allergic patients' sera, the results corroborated to that of skin prick test. Comparison of allergen profiles of the two fish extracts by immunoblotting revealed a common antigenic protein of 50 kDa and some high molecular weight fish allergens instead of low molecular weight parvalbumin found in several fishes. Purified and well characterized fish allergens are always considered better than crude fish extracts for diagnostic use.

Research paper thumbnail of Activation dependent expression of MMPs in peripheral blood mononuclear cells involves protein kinase A

Molecular and Cellular Biochemistry, 2006

Monocyte/Macrophages are integral cellular components of inflammation. Matrix metalloproteinases ... more Monocyte/Macrophages are integral cellular components of inflammation. Matrix metalloproteinases (MMPs) produced by these cells play a crucial role in every aspect of inflammation. Results of the investigations on activation dependent upregulation of MMPs in human peripheral blood mononuclear cells in culture using different lectins as an in vitro model system to mimic inflammatory monocytes are presented. Under normal physiological conditions the monocytes produced only very low amount of MMPs in an indomethacin insensitive PG/cAMP independent manner. Zymographic analysis and ELISA showed that treatment of monocyte with lectins like concanavalin A (ConA), wheat germ agglutinin (WGA) and Artocarpus lakoocha agglutinin (ALA) caused upregulation of MMPs and the maximum effect was produced by ALA. ALA significantly upregulated MMP-9 in a concentration and time dependent manner. Immunoblot analysis and RT-PCR confirmed ALA mediated upregulation of MMP-9 production. Inhibition of ALA effect by indomethacin and reversal of the indomethacin effect by Bt(2)cAMP indicated involvement of cAMP dependent signaling pathway. Further support for the prostaglandin mediated effect was obtained by the upregulation of cyclooxygenase by ALA. H-89, an inhibitor of protein kinase A (PKA), inhibited the expression of MMP-9 indicating that ALA mediated upregulation of MMP-9 is mediated through PKA pathway. Increase in MMP production and increase in cyclooxygenase activity and inhibition of the effect of ALA on MMP production by indomethacin suggested that the ALA activated monocytes in culture can be used as an in vitro model system to study the intracellular signaling process involved in the mediation of inflammatory response.

Research paper thumbnail of Alterations of glycan branching and differential expression of sialic acid on alpha fetoprotein among hepatitis patients

Glycoconjugate Journal, 2010

The level of serum glycoproteins and their glycosylation pattern change in liver diseases includi... more The level of serum glycoproteins and their glycosylation pattern change in liver diseases including hepatocellular carcinoma (HCC). Some of them, especially alpha fetoprotein (AFP), serve as useful biomarkers for HCC. The present investigation showed high level of AFP in hepatitis B cirrhosis (HBV-LC) and hepatitis C cirrhosis (HCV-LC) patients. However, increase of AFP level was not significantly high in chronic hepatitis B (HBV-CH) as determined by ELISA using monoclonal anti-human AFP (mAb-AFP). The differential expression of sialic acid linkage was observed in HBV-CH and HCV-LC by ELISA; the former bound strongly with Sambucus nigra agglutinin (SNA), which has exclusive binding specificity for NeuAcα2-6-, whereas HCV-LC reacted preferably with Maackia amurensis agglutinin (MAA) which recognizes NeuAcα2-3-. There was significantly high glycan branching in HBV-LC and HCV-LC in comparison to controls as illustrated by concanavalin A. This was further confirmed by Phaseolus vulgaris erythroagglutinin (E-PHA) and Datura stramonium agglutinin (DSA). Enhanced fucosylation of AFP was observed in HBV-LC, HCV-LC and HCC patients by ELISA using fucose binding Aleuria aurantia lectin; however, maximum binding was found in HCC. Fucosylation with α1-6 linkage was further confirmed by Lens culinaris agglutinin (LCA). From the above results it is concluded that the changes in concentration of AFP, differential expression of sialic acid, increase of glycan branching and fucosylation have a prognostic value of hepatitis and it could be possible that lectin-based assay with AFP can aid in diagnosis of hepatitis diseases besides clinical examination and routine laboratory investigation.

Research paper thumbnail of Antiproliferative effect of T/Tn specific Artocarpus lakoocha agglutinin (ALA) on human leukemic cells (Jurkat, U937, K562) and their imaging by QD-ALA nanoconjugate

Glycoconjugate Journal, 2008

T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha ... more T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha (Moraceae) fruit and a heterodimer (16 kD and 12 kD) of molecular mass 28 kD, was further confirmed by SPR analysis using T/ Tn glycan containing mammalian glycoproteins. N-terminal amino acid sequence analysis of ALA showed homology at 15, 19-21, 24-27, and 29 residues with other lectin members of Moraceae family viz., Artocarpus integrifolia (jacalin) lectin, Artocarpus hirsuta lectin, and Maclura pomifera agglutinin. It is mitogenic to human PBMC and the maximum proliferation was observed at 1 ng/ml. It showed an antiproliferative effect on leukemic cells, with the highest effect toward Jurkat cells (IC 50 13.15 ng/ml). Synthesized CdS quantum dot-ALA nanoconjugate was employed to detect the expression of T/Tn glycans on Jurkat, U937, and K562 leukemic cells surfaces as well as normal lymphocytes by fluorescence microscopy. No green fluorescence was observed with normal lymphocytes indicating that T/Tn determinants, which are recognized as human tumor associated structures were cryptic on normal lymphocyte surfaces, whereas intense green fluorescent dots appeared during imaging of leukemic cells, where such determinants were present in unmasked form. The above results indicated that QD-ALA nanoconjugate is an efficient fluorescent marker for identification of leukemic cell lines that gives rise to high quality images. Keywords ALA. Artocarpus lakoocha agglutinin. Surface plasmon resonance. Leukemic cells. Quantum dot. Nanoconjugate Abbreviations ALA Artocarpus lakoocha agglutinin BSM Bovine submandibular gland mucin CdS Cadmium sulphide ELLSA Enzyme-linked lectinsorbent assay ESI-MS Electron spray ionization mass spectrometry FPLC Fast protein liquid chromatography HBS Hepes buffered saline HEPES N-(2-hydoxyethyl) piperizine-N′-(2-hydroxypropane sulfonic acid) HSM Hamster submaxillary mucin PBMC Peripheral blood mononuclear cells PVDF Polyvinylidene difluoride

Research paper thumbnail of Enhanced expression of α1-acid glycoprotein and fucosylation in hepatitis B patients provides an insight into pathogenesis

Glycoconjugate Journal, 2009

Altered glycosylation and concentration of α1acid glycoprotein has been known to be related to th... more Altered glycosylation and concentration of α1acid glycoprotein has been known to be related to the pathogenesis of the hepatic diseases. The present study investigated enhanced fucosylation of AGP in the sera of chronic hepatitis B (HBV-CH) and hepatitis B cirrhosis (HBV-LC) patients by high performance anion exchange chromatography and by ELISA using fucose binding Aleuria aurantia lectin. The concentration of AGP determined by ELISA using monoclonal anti-human AGP (mAb-AGP) showed high level of AGP in HBV-CH and HBV-LC patients. This was further judged by association constant (K A) measured by surface plasmon resonance analysis. There was no apparent linkage variation of sialic acid among different patient groups when tested with two sialic acid binding lectins viz., Maackia amurensis agglutinin (MAA, NeuAc α2-3-) and Sambucus nigra agglutinin (SNA, NeuAc α2-6-) respectively. There was no change of oligosaccharide branching in HBV-CH in comparison to controls whereas a slight change was observed in HBV-LC using ConA. The above results suggest that the changes in concentration of AGP and fucosylation have a prognostic value of hepatitis diseases and it could be possible to use AGP as diagnostic marker besides clinical examination and routine laboratory investigation. Keywords α1-Acid glycoprotein. Fucosylation. High performance anion-exchange chromatography. SPR. ELISA. 2-D gel electrophoresis Abbreviations AAL Aleuria aurantia lectin AGP α1-Acid glycoprotein HBV Hepatitis B virus HBV-CH Chronic viral hepatitis B HBV-LC Viral hepatitis B cirrhosis HCC Hepatocellular carcinoma HPAEC-PAD High performance anion exchange chromatography pulse amperometric detection MAA Maackia amurensis agglutinin SD Standard deviation SNA Sambucus nigra agglutinin SPR Surface plasmon resonance

Research paper thumbnail of Carbohydrate recognition factors of a T  (Gal 1->3GalNAc 1->Ser/Thr) and Tn (GalNAc 1->Ser/Thr) specific lectin isolated from the seeds of Artocarpus lakoocha

Glycobiology, 2004

Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha fruit, is a galactos... more Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha fruit, is a galactose-binding lectin and a potent mitogen of T and B cells. Knowledge obtained from previous studies on the affinity of ALA was limited to molecular and submolecular levels of Galb1!3GalNAc (T) and its derivatives. In the present study, the carbohydrate specificity of ALA was characterized at the macromolecular level according to the mammalian Gal/GalNAc structural units and corresponding glycoconjugates by an enzyme-linked lectinosorbent (ELLSA) and inhibition assays. The results indicate that ALA binds specifically to tumor-associated carbohydrate antigens GalNAca1!Ser/Thr (Tn) and Galb1!3 GalNAca1!Ser/Thr (T a). It barely cross-reacts with other common glycotopes on glycoproteins, including ABH blood group antigens, Galb1!3/4GlcNAc (I/II) determinants, T/Tn covered by sialic acids, and N-linked plasma glycoproteins. Dense clustering structure of Tn/T a-containing glycoproteins tested resulted in 2.4 Â 10 5-6.7 Â 10 5-fold higher affinities to ALA than the respective GalNAc and Gal monomer. According to our results, the overall affinity of ALA for glycans can be ranked respectively: polyvalent Tn/ T a glycotopes) monomeric T a and simple clustered Tn) monomeric Tn 4 GalNAc 4 Gal; while other glycotopes: Gala1!3/4Gal (B/E), Galb1!3/4GlcNAc (I/II), Gal-NAca1!3Gal/GalNAc (A/F), and GalNAcb1!3/4Gal (P/ S) were inactive. The strong specificity of ALA for Tn/T a cluster suggests the importance of glycotope polyvalency during carbohydrate-receptor interactions and emphasizes its value as an anti-Tn/T lectin for analysis of glycoconjugate mixtures or transformed carbohydrates.

Research paper thumbnail of Artificial spider silk supports and guides neurite extension in vitro

The FASEB Journal, 2021

This is an open access article under the terms of the Creat ive Commo ns Attri butio n-NonCo mmer... more This is an open access article under the terms of the Creat ive Commo ns Attri butio n-NonCo mmerc ial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Research paper thumbnail of Spidroin N-terminal domain forms amyloid-like fibril based hydrogels and provides a protein immobilization platform

Nature Communications

Recombinant spider silk proteins (spidroins) have multiple potential applications in development ... more Recombinant spider silk proteins (spidroins) have multiple potential applications in development of novel biomaterials, but their multimodal and aggregation-prone nature have complicated production and straightforward applications. Here, we report that recombinant miniature spidroins, and importantly also the N-terminal domain (NT) on its own, rapidly form self-supporting and transparent hydrogels at 37 °C. The gelation is caused by NT α-helix to β-sheet conversion and formation of amyloid-like fibrils, and fusion proteins composed of NT and green fluorescent protein or purine nucleoside phosphorylase form hydrogels with intact functions of the fusion moieties. Our findings demonstrate that recombinant NT and fusion proteins give high expression yields and bestow attractive properties to hydrogels, e.g., transparency, cross-linker free gelation and straightforward immobilization of active proteins at high density.

Research paper thumbnail of Nutritional Implications of Algal Polysaccharides

Research paper thumbnail of Advances in early diagnosis of hepatocellular carcinoma

Hepatoma Research, 2019

Hepatocellular carcinoma (HCC) is the most recurrent hepatic malignancy and the third in the canc... more Hepatocellular carcinoma (HCC) is the most recurrent hepatic malignancy and the third in the cancer-related casualties in the west. The frequently-documented causes of HCC are chronic liver infections by hepatitis B virus or hepatitis C virus, nonalcoholic fatty liver disease, cirrhosis, exposure to aflatoxins and tobacco smocking, etc. Clinical presentation of this fatal disease ranges from asymptomatic to upper abdominal pain or common health conditions like weight loss or lethargy. Among current surveillance strategy for suspected patients, liver imaging and serum alpha fetoprotein estimation has been regularly recommended. However, sensitivity of this diagnostic methodology especially in early detections, often suffers from compromised sensitivity and selectivity. Various image based and serological biomarkers for HCC has been introduced in recent decades with varied sensitivity as stand-alone or combined diagnostic protocol. The current article will review the status of HCC diagnosis with respect to common diagnostic protocol, and upcoming novel biomarkers.

Research paper thumbnail of Assessment of Altered Fucosylation of Serum α-1-Acid Glycoprotein in Hepatocellular Carcinoma Patients by Gold-Nanoparticle Aggregation Immunoassay

Material Science Research India, 2018

Gold nanoparticles have attracted considerable attention due to their unique properties and poten... more Gold nanoparticles have attracted considerable attention due to their unique properties and potential applications as optical probes. When proteins that are adsorbed on gold nanoparticles subsequently get cross-linked by any interaction specific to that protein, the size of the aggregates increases and this enhancement of size have been used for sensitive, convenient and powerful tool to monitor the presence of the specific cross-linkers. Dynamic light scattering (DLS) is a technique that is routinely used for detecting aggregation in macromolecular solutions. In this work, we first applied DLS to identify specific glycoprotein–lectin interactions exclusively present in the serum of hepatocellular carcinoma patients compared to healthy controls that showed the altered fucosylation of a serum protein, Serum α-1-Acid glycoprotein. Further, based on the DLS data a simple, rapid, serological assay was developed based on antibody coated gold nanoparticle and fucose binding lectin (Aleuri...

Research paper thumbnail of Biological activity of marine sponge lectins

Marine Glycobiology, 2016

Research paper thumbnail of Gold nanoparticle-based novel visual diagnostic method for the detection of specific IgE to test for food allergies

Analytical Methods, 2016

Visual test for food allergy by GNP-based plasmonic detection of specific IgE in sera.

Research paper thumbnail of Effects of Congo red on aβ(1-40) fibril formation process and morphology

ACS chemical neuroscience, Jan 21, 2010

Alzheimer's disease (AD), an age-related neurodegenerative disorder, is the most common form ... more Alzheimer's disease (AD), an age-related neurodegenerative disorder, is the most common form of dementia, and the seventh-leading cause of death in the United States. Current treatments offer only symptomatic relief; thus, there is a great need for new treatments with disease-modifying potential. One pathological hallmark of AD is so-called senile plaques, mainly made up of β-sheet-rich assemblies of 40- or 42-residue amyloid β-peptides (Aβ). Hence, inhibition of Aβ aggregation is actively explored as an option to prevent or treat AD. Congo red (CR) has been widely used as a model antiamyloid agent to prevent Aβ aggregation. Herein, we report detailed morphological studies on the effect of CR as an antiamyloid agent, by circular dichroism spectroscopy, photo-induced cross-linking reactions, and atomic force microscopy. We also demonstrate the effect of CR on a preaggregated sample of Aβ(1-40). Our result suggests that Aβ(1-40) follows a different path for aggregation in the pres...

Research paper thumbnail of Poly-N-methylated Amyloid β-Peptide (Aβ) C-Terminal Fragments Reduce Aβ Toxicity in Vitro and in Drosophila melanogaster

Journal of Medicinal Chemistry, 2009

Alzheimer&amp... more Alzheimer's disease (AD), an age related neurodegenerative disorder, threatens to become a major health-economic problem. Assembly of 40- or 42-residue amyloid beta-peptides (Abeta) into neurotoxic oligo-/polymeric beta-sheet structures is an important pathogenic feature in AD, thus, inhibition of this process has been explored to prevent or treat AD. The C-terminal part plays an important role in Abeta aggregation, but most Abeta aggregation inhibitors have targeted the central region around residues 16-23. Herein, we synthesized hexapeptides with varying extents of N-methylation based on residues 32-37 of Abeta, to target its C-terminal region. We measured the peptides' abilities to retard beta-sheet and fibril formation of Abeta and to reduce Abeta neurotoxicity. A penta-N-methylated peptide was more efficient than peptides with 0, 2, or 3 N-methyl groups. This penta-N-methylated peptide moreover increased life span and locomotor activity in Drosophila melanogaster flies overexpressing human Abeta(1-42).

Research paper thumbnail of In vitro ADMET and physicochemical investigations of poly-N-methylated peptides designed to inhibit Aβ aggregation

Bioorganic & Medicinal Chemistry, 2010

N-Methylation is a common strategy for improving oral bioavailability of peptide-based lead struc... more N-Methylation is a common strategy for improving oral bioavailability of peptide-based lead structures. Herein, we present a detailed study on how the degree of N-methylation affects the absorption-distribution-metabolism-excretion-toxicity (ADMET) properties such as solubility, membrane transport, proteolytic stability, and general cell toxicity of the investigated peptides. As representative structures we chose hexapeptides 1-8. These peptides, corresponding to N-methylated analogues of residues 16-21 and 32-37 of the Abeta-peptide, pathological hallmark of Alzheimer's disease (AD), have previously been shown to inhibit aggregation of Abeta fibrils in vitro. This study suggests that poly-N-methylated peptides are non-toxic and have enhanced proteolytic stability over their non-methylated analogues. Furthermore, solubility in aqueous solution is seen to increase with increased degree of N-methylation, while membrane transport was found to be low for all investigated hexapeptides. The present results, together with those reported in the literature, suggest that poly-N-methylated peptides, especially shorter or equal to six residues, can be suitable candidates for drug design.

Research paper thumbnail of Effects of Congo Red on A� 1-40 Fibril Formation Process and Morphology

Acs Chemical Neuroscience, 2010

Research paper thumbnail of Chitosan as a Universal Drug Delivery Vehicle

Encyclopedia of Marine Biotechnology, 2020

Research paper thumbnail of Role of pepsin in modifying the allergenicity of bhetki (Lates calcarifer) and mackerel (Rastrelliger kanagurta) fish

Indian journal of biochemistry & biophysics, 2007

The effect of pepsin digestion on the allergenicity of raw and thermally processed (boiled and fr... more The effect of pepsin digestion on the allergenicity of raw and thermally processed (boiled and fried) fish muscle extracts of two widely consumed fishes bhetki (Lates calcarifer) and mackerel (Rastrelliger kanagurta) was studied. Sere were collected from 110 patients who were hypersensitive to fish, as evidenced by their clinical history, symptoms and positive skin-prick test results. The various extracts after digestion with pepsin at different times of incubation were tested for specific IgE-binding activity by ELISA and immunoblotting with patients' sera. All the extracts of both the fishes retained their allergenicity as evidenced by ELISA and immunoblotting. In bhetki, maximum allergenicity was found in the pepsin-digested fried extract, whereas similar treatment decreased the allergenicity in fried mackerel. Results showed that raw as well as thermally processed allergens of both the fishes maintained strong allergenicity, even after digestion with pepsin for different tim...

Research paper thumbnail of Identification of allergens in Indian fishes: hilsa and pomfret exemplified by ELISA and immunoblotting

Indian journal of experimental biology, 2005

Enzymed-linked immunosorbent assay of hilsa and pomfret muscle extracts showed specific IgE bindi... more Enzymed-linked immunosorbent assay of hilsa and pomfret muscle extracts showed specific IgE binding to ten allergic patients' sera, the results corroborated to that of skin prick test. Comparison of allergen profiles of the two fish extracts by immunoblotting revealed a common antigenic protein of 50 kDa and some high molecular weight fish allergens instead of low molecular weight parvalbumin found in several fishes. Purified and well characterized fish allergens are always considered better than crude fish extracts for diagnostic use.

Research paper thumbnail of Activation dependent expression of MMPs in peripheral blood mononuclear cells involves protein kinase A

Molecular and Cellular Biochemistry, 2006

Monocyte/Macrophages are integral cellular components of inflammation. Matrix metalloproteinases ... more Monocyte/Macrophages are integral cellular components of inflammation. Matrix metalloproteinases (MMPs) produced by these cells play a crucial role in every aspect of inflammation. Results of the investigations on activation dependent upregulation of MMPs in human peripheral blood mononuclear cells in culture using different lectins as an in vitro model system to mimic inflammatory monocytes are presented. Under normal physiological conditions the monocytes produced only very low amount of MMPs in an indomethacin insensitive PG/cAMP independent manner. Zymographic analysis and ELISA showed that treatment of monocyte with lectins like concanavalin A (ConA), wheat germ agglutinin (WGA) and Artocarpus lakoocha agglutinin (ALA) caused upregulation of MMPs and the maximum effect was produced by ALA. ALA significantly upregulated MMP-9 in a concentration and time dependent manner. Immunoblot analysis and RT-PCR confirmed ALA mediated upregulation of MMP-9 production. Inhibition of ALA effect by indomethacin and reversal of the indomethacin effect by Bt(2)cAMP indicated involvement of cAMP dependent signaling pathway. Further support for the prostaglandin mediated effect was obtained by the upregulation of cyclooxygenase by ALA. H-89, an inhibitor of protein kinase A (PKA), inhibited the expression of MMP-9 indicating that ALA mediated upregulation of MMP-9 is mediated through PKA pathway. Increase in MMP production and increase in cyclooxygenase activity and inhibition of the effect of ALA on MMP production by indomethacin suggested that the ALA activated monocytes in culture can be used as an in vitro model system to study the intracellular signaling process involved in the mediation of inflammatory response.

Research paper thumbnail of Alterations of glycan branching and differential expression of sialic acid on alpha fetoprotein among hepatitis patients

Glycoconjugate Journal, 2010

The level of serum glycoproteins and their glycosylation pattern change in liver diseases includi... more The level of serum glycoproteins and their glycosylation pattern change in liver diseases including hepatocellular carcinoma (HCC). Some of them, especially alpha fetoprotein (AFP), serve as useful biomarkers for HCC. The present investigation showed high level of AFP in hepatitis B cirrhosis (HBV-LC) and hepatitis C cirrhosis (HCV-LC) patients. However, increase of AFP level was not significantly high in chronic hepatitis B (HBV-CH) as determined by ELISA using monoclonal anti-human AFP (mAb-AFP). The differential expression of sialic acid linkage was observed in HBV-CH and HCV-LC by ELISA; the former bound strongly with Sambucus nigra agglutinin (SNA), which has exclusive binding specificity for NeuAcα2-6-, whereas HCV-LC reacted preferably with Maackia amurensis agglutinin (MAA) which recognizes NeuAcα2-3-. There was significantly high glycan branching in HBV-LC and HCV-LC in comparison to controls as illustrated by concanavalin A. This was further confirmed by Phaseolus vulgaris erythroagglutinin (E-PHA) and Datura stramonium agglutinin (DSA). Enhanced fucosylation of AFP was observed in HBV-LC, HCV-LC and HCC patients by ELISA using fucose binding Aleuria aurantia lectin; however, maximum binding was found in HCC. Fucosylation with α1-6 linkage was further confirmed by Lens culinaris agglutinin (LCA). From the above results it is concluded that the changes in concentration of AFP, differential expression of sialic acid, increase of glycan branching and fucosylation have a prognostic value of hepatitis and it could be possible that lectin-based assay with AFP can aid in diagnosis of hepatitis diseases besides clinical examination and routine laboratory investigation.

Research paper thumbnail of Antiproliferative effect of T/Tn specific Artocarpus lakoocha agglutinin (ALA) on human leukemic cells (Jurkat, U937, K562) and their imaging by QD-ALA nanoconjugate

Glycoconjugate Journal, 2008

T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha ... more T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha (Moraceae) fruit and a heterodimer (16 kD and 12 kD) of molecular mass 28 kD, was further confirmed by SPR analysis using T/ Tn glycan containing mammalian glycoproteins. N-terminal amino acid sequence analysis of ALA showed homology at 15, 19-21, 24-27, and 29 residues with other lectin members of Moraceae family viz., Artocarpus integrifolia (jacalin) lectin, Artocarpus hirsuta lectin, and Maclura pomifera agglutinin. It is mitogenic to human PBMC and the maximum proliferation was observed at 1 ng/ml. It showed an antiproliferative effect on leukemic cells, with the highest effect toward Jurkat cells (IC 50 13.15 ng/ml). Synthesized CdS quantum dot-ALA nanoconjugate was employed to detect the expression of T/Tn glycans on Jurkat, U937, and K562 leukemic cells surfaces as well as normal lymphocytes by fluorescence microscopy. No green fluorescence was observed with normal lymphocytes indicating that T/Tn determinants, which are recognized as human tumor associated structures were cryptic on normal lymphocyte surfaces, whereas intense green fluorescent dots appeared during imaging of leukemic cells, where such determinants were present in unmasked form. The above results indicated that QD-ALA nanoconjugate is an efficient fluorescent marker for identification of leukemic cell lines that gives rise to high quality images. Keywords ALA. Artocarpus lakoocha agglutinin. Surface plasmon resonance. Leukemic cells. Quantum dot. Nanoconjugate Abbreviations ALA Artocarpus lakoocha agglutinin BSM Bovine submandibular gland mucin CdS Cadmium sulphide ELLSA Enzyme-linked lectinsorbent assay ESI-MS Electron spray ionization mass spectrometry FPLC Fast protein liquid chromatography HBS Hepes buffered saline HEPES N-(2-hydoxyethyl) piperizine-N′-(2-hydroxypropane sulfonic acid) HSM Hamster submaxillary mucin PBMC Peripheral blood mononuclear cells PVDF Polyvinylidene difluoride

Research paper thumbnail of Enhanced expression of α1-acid glycoprotein and fucosylation in hepatitis B patients provides an insight into pathogenesis

Glycoconjugate Journal, 2009

Altered glycosylation and concentration of α1acid glycoprotein has been known to be related to th... more Altered glycosylation and concentration of α1acid glycoprotein has been known to be related to the pathogenesis of the hepatic diseases. The present study investigated enhanced fucosylation of AGP in the sera of chronic hepatitis B (HBV-CH) and hepatitis B cirrhosis (HBV-LC) patients by high performance anion exchange chromatography and by ELISA using fucose binding Aleuria aurantia lectin. The concentration of AGP determined by ELISA using monoclonal anti-human AGP (mAb-AGP) showed high level of AGP in HBV-CH and HBV-LC patients. This was further judged by association constant (K A) measured by surface plasmon resonance analysis. There was no apparent linkage variation of sialic acid among different patient groups when tested with two sialic acid binding lectins viz., Maackia amurensis agglutinin (MAA, NeuAc α2-3-) and Sambucus nigra agglutinin (SNA, NeuAc α2-6-) respectively. There was no change of oligosaccharide branching in HBV-CH in comparison to controls whereas a slight change was observed in HBV-LC using ConA. The above results suggest that the changes in concentration of AGP and fucosylation have a prognostic value of hepatitis diseases and it could be possible to use AGP as diagnostic marker besides clinical examination and routine laboratory investigation. Keywords α1-Acid glycoprotein. Fucosylation. High performance anion-exchange chromatography. SPR. ELISA. 2-D gel electrophoresis Abbreviations AAL Aleuria aurantia lectin AGP α1-Acid glycoprotein HBV Hepatitis B virus HBV-CH Chronic viral hepatitis B HBV-LC Viral hepatitis B cirrhosis HCC Hepatocellular carcinoma HPAEC-PAD High performance anion exchange chromatography pulse amperometric detection MAA Maackia amurensis agglutinin SD Standard deviation SNA Sambucus nigra agglutinin SPR Surface plasmon resonance

Research paper thumbnail of Carbohydrate recognition factors of a T  (Gal 1->3GalNAc 1->Ser/Thr) and Tn (GalNAc 1->Ser/Thr) specific lectin isolated from the seeds of Artocarpus lakoocha

Glycobiology, 2004

Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha fruit, is a galactos... more Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha fruit, is a galactose-binding lectin and a potent mitogen of T and B cells. Knowledge obtained from previous studies on the affinity of ALA was limited to molecular and submolecular levels of Galb1!3GalNAc (T) and its derivatives. In the present study, the carbohydrate specificity of ALA was characterized at the macromolecular level according to the mammalian Gal/GalNAc structural units and corresponding glycoconjugates by an enzyme-linked lectinosorbent (ELLSA) and inhibition assays. The results indicate that ALA binds specifically to tumor-associated carbohydrate antigens GalNAca1!Ser/Thr (Tn) and Galb1!3 GalNAca1!Ser/Thr (T a). It barely cross-reacts with other common glycotopes on glycoproteins, including ABH blood group antigens, Galb1!3/4GlcNAc (I/II) determinants, T/Tn covered by sialic acids, and N-linked plasma glycoproteins. Dense clustering structure of Tn/T a-containing glycoproteins tested resulted in 2.4 Â 10 5-6.7 Â 10 5-fold higher affinities to ALA than the respective GalNAc and Gal monomer. According to our results, the overall affinity of ALA for glycans can be ranked respectively: polyvalent Tn/ T a glycotopes) monomeric T a and simple clustered Tn) monomeric Tn 4 GalNAc 4 Gal; while other glycotopes: Gala1!3/4Gal (B/E), Galb1!3/4GlcNAc (I/II), Gal-NAca1!3Gal/GalNAc (A/F), and GalNAcb1!3/4Gal (P/ S) were inactive. The strong specificity of ALA for Tn/T a cluster suggests the importance of glycotope polyvalency during carbohydrate-receptor interactions and emphasizes its value as an anti-Tn/T lectin for analysis of glycoconjugate mixtures or transformed carbohydrates.

Research paper thumbnail of Artificial spider silk supports and guides neurite extension in vitro

The FASEB Journal, 2021

This is an open access article under the terms of the Creat ive Commo ns Attri butio n-NonCo mmer... more This is an open access article under the terms of the Creat ive Commo ns Attri butio n-NonCo mmerc ial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.