Soghra Haq | Omar Al-Mukhtar University, Tobruk (original) (raw)

Papers by Soghra Haq

Research paper thumbnail of Isolation and Biochemical characterization of Protein Proteinase Inhibitors from Cajanus Cajan and Phaseolus Aureus

Research paper thumbnail of Identification and Characterization of Functional Intermediates of Stem Bromelain During Urea and Guanidine Hydrochloride Unfolding

Journal of Biochemistry, Dec 26, 2006

Research paper thumbnail of Bone morphogenic protein-7 (BMP-7) polymorphism: Susceptibility to cirrhosis and hepatocellular carcinoma after viral hepatitis in Egyptian patients

Clinical and Experimental Hepatology

Aim of the study: Bone morphogenic proteins (BMPs) have both inhibitory and stimulatory effects o... more Aim of the study: Bone morphogenic proteins (BMPs) have both inhibitory and stimulatory effects on growth of a tumor that depend on the type of cells, the dosage and the tumor microenvironment. We aimed to investigate the impact of the bone morphogenic protein-7 (BMP-7) single nucleotide polymorphism (SNP) rs230205 [A/G] on susceptibility to hepatocellular carcinoma (HCC) progression from liver cirrhosis after viral hepatitis infection in Egyptian patients. Material and methods: The amplification-refractory mutation system (ARMS)-polymerase chain reaction (PCR) method was used to genotype the rs230205 [A/G] SNP in 150 subjects (50 patients with post-hepatitis C or B cirrhosis, 50 HCC patients, and 50 controls). Expression level of BMP-7 protein was assessed using enzyme-linked immunosorbent assay (ELISA). Results: The results revealed insignificant changes in distribution of all genotypes/alleles of the BMP-7 rs230205 [A/G] SNP between cirrhotic patients, HCC patients and controls. The AA genotype and A allele could be considered risk factors for cirrhosis (OR = 1.75, 1.50) and HCC (OR = 2.19, 1.74), respectively. The AA genotype (95% CI: 0.45-6.79) and A allele (OR = 1.50, 95% CI: 0.77-2.93) may be viewed as cirrhosis risk factors based on group segregation. Additionally, the A allele, AG and AA genotypes and their combined ORs of 2.19 (95% CI: 0.58-8.23), 1.74 (95% CI: 0.90-3.37), and 1.70 (95% CI: 0.68-4.29) could all be risk factors for HCC. No genotype or allele could be regarded as a risk factor for progression of cirrhosis to HCC, according to OR values. Conclusions: The results showed no correlation between BMP-7 rs230205 [A/G] SNP and progression of cirrhosis to HCC. To confirm our findings, additional prospective large-scale research is required.

Research paper thumbnail of Acceptance, hesitancy, and refusal of coronavirus disease 2019 vaccine and associated factors in the population of Libya: A cross-sectional study

Libyan Journal of Medical Sciences

Research paper thumbnail of Trends in varicella epidemiology among an unvaccinated population: first results from Libya

Archives of Disease in Childhood

Research paper thumbnail of Clinical Characteristics of the First 100 Patients of COVID-19 in Tobruk, Libya: A Brief Report From Low-Resource Settings

Disaster Medicine and Public Health Preparedness

Objective:This study aims to report the clinical features of a cohort of patients with suspected ... more Objective:This study aims to report the clinical features of a cohort of patients with suspected coronavirus disease (COVID-19) from Tobruk, Libya, and reflect upon the diagnosis challenge in low-resource settings.Methods:A descriptive report of the first 100 patients with suspected COVID-19 who have visited the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and COVID-19 screening clinic at the National Centre for Disease Control in Tobruk, Libya.Results:The most common presenting symptoms were fever (90%), cough (89%), dyspnea (85%), sore throat (79%), fatigue (78%), headache (64%), loss of smell (52%), loss of taste (53%), loss of appetite (43%), nausea and vomiting (26%), diarrhea (22%), and rhinorrhea (16%); 51% of the patients had lymphocytopenia, whereas 13% had thrombocytopenia. Bilateral infiltrates were the most common radiologic finding on chest X-ray (76%), and COVID-19 IgM and/or IgG antibodies were detected in 80% of the patients, whereas only 37% of the p...

Research paper thumbnail of TB in eastern Libya: a decreasing trend in recent decades

The International Journal of Tuberculosis and Lung Disease

Research paper thumbnail of Hepatitis C Virus Infection in Eastern Libya: Efforts Needed to Improve HCV Testing and Linkage to Care in the Resource-Limited Setting

Tropical Medicine and Infectious Disease, 2022

Hepatitis C virus (HCV) is a significant public health problem, and the elimination of its infect... more Hepatitis C virus (HCV) is a significant public health problem, and the elimination of its infection by 2031 is a global goal. However, due to insufficient testing, lack of linkage to care (LTC) and treatment, Libya may be far from achieving this goal. This study aimed to explore HCV testing, the care and treatment of infected people, and to assess the burden of the infection among individuals who visited the main Medical Centre in Tobruk region, eastern Libya, for various medical and surgical conditions. A research team interviewed public health officials in Tobruk Medical Center, inspected available equipment, and obtained data available for people who were positive for antibodies to HCV (anti-HCV) as part of their routine pre-invasive procedures and pre-donation screening tests from January 2005 to April 2020. HCV antibody tests were positive for 612 cases out of 368,392 (0.17%). Of those who tested positive for anti-HCV antibodies, no one had followed up by RNA test for identify...

Research paper thumbnail of Antibiotic resistance patterns of urinary pathogens in outpatients and inpatients: A report from Eastern Libya

International Journal of Urological Nursing, 2021

Urinary tract infections (UTIs) are one of the most common infections and remain a public health ... more Urinary tract infections (UTIs) are one of the most common infections and remain a public health problem worldwide. Incidence of UTI‐causing pathogens and their antibiotic susceptibility are varied in different regions. To examine the frequency of UTIs among inpatients and outpatients at Tobruk Medical Centre, Eastern Libya to identify the UTIs most common causative agents, and to assess their resistance patterns to the commonly used antibiotics. A laboratory registry‐based retrospective survey included 25 388 urine samples obtained from symptomatic UTIs cases that attended the Tobruk Medical Centre in the period from January 2006 to December 2018. Antimicrobial susceptibility testing and bacterial identification were done as per the microbiology lab's standard operating procedure. The frequency of UTIs and their resistance patterns were examined in inpatients and outpatients. Out of 25 388 urine samples tested, 6838 (26.9%) showed growth of pathogens indicative of positive UTI....

Research paper thumbnail of Identification and characterization of functional intermediates of stem bromelain during urea and guanidine hydrochloride unfolding

Journal of biochemistry, 2007

By comparing changes in enzyme activity with changes in spectral features for stem bromelain (EC.... more By comparing changes in enzyme activity with changes in spectral features for stem bromelain (EC.3.4.22.32) in the absence and presence of urea, Guanidine hydrochloride and ethanol; four intermediate states could be identified: two activity-enhanced state obtained in the presence of 5 M urea and 2 M GnHCl, termed X and X', respectively, and a third, similarly active state closely resembling the native protein in the presence of 8-9 M urea, termed Y. The enhanced activity of these states is due to local conformational changes accompanied by increased dynamics in the active site. Further, the enzyme does not lose its activity after substantial tertiary structure changes in 8-9 M urea (Y state), suggesting that active site containing domain is more resistant to chemical denaturation than the other structural domain. This makes stem bromelain and in general cysteine proteases an exception to the hypothesis that active site is the most labile part of enzyme.

Research paper thumbnail of Methylmercury

Research paper thumbnail of Effect of trifluoroethanol on native and acid-induced states of glucose oxidase from Aspergillus niger

Biochemistry (Moscow), 2010

We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.... more We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.6), and molten globule (pH 1.4) states of glucose oxidase (GOX) by circular dichroism and fluorescence spectroscopy. In the presence of 50% TFE, at pH 7.0 and 2.6, GOX exhibited a transition from native coiled-coil and acid unfolded state to non-associating alpha-helical state. Interestingly, at pH 1.4, 15% TFE induced the formation of beta-structured intermediate by loss of 1-anilino-8-naphthalenesulfonate binding site and almost all tertiary contacts. The beta-structured intermediate converted into open helical conformation on further addition of TFE.

Research paper thumbnail of Low SARS-CoV-2 Antibodies in Blood Donors After the First 6 Months of COVID-19 Epidemic in the Tobruk Region, Eastern Libya

Disaster Medicine and Public Health Preparedness

Coronavirus disease 2019 (COVID-19) is primarily a respiratory virus and there is no evidence of ... more Coronavirus disease 2019 (COVID-19) is primarily a respiratory virus and there is no evidence of transfusion transmission for COVID-19;1, 2 however, estimation of the seroprevalence rate of antibodies to severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) in blood donors’ population reflects the progression of the epidemic in the region. It is unclear how many people have contracted the virus since only symptomatic cases have been registered. For this reason, and as a part of the National Centre for Disease Control preparedness plan to combat the spread of the COVID-19 infection in the Tobruk region, eastern Libya, we conducted a cross-sectional study between January 15 to February 15, 2021, six months after the identification of the first confirmed COVID-19 case in the region on 23 July 2020. 3

Research paper thumbnail of Spectroscopic analysis of thermal denaturation of Cajanus cajan proteinase inhibitor at neutral and acidic pH by circular dichroism

International Journal of Biological Macromolecules, 2005

The conformational changes accompanying thermal denaturation under neutral, acidic and reducing c... more The conformational changes accompanying thermal denaturation under neutral, acidic and reducing conditions of Cajanus cajan proteinase inhibitor were investigated using near- and far-ultraviolet circular dichroism (CD) spectroscopy. The protein inhibitor shows a reversible N ↔ D transition at neutral pH with a Tm approximately equal to 63 °C. The negative CD band intensities at 200 nm (far-UV) and near about 280 nm (near-UV) decrease as a result of thermal stress. The effect is more pronounced at low pH and in the presence of dithiothreitol. Only partial reversibility is observed under acidic conditions. Significant changes in the near- as well as far-ultraviolet CD spectrum are observed in the presence of dithiothreitol suggestive of the importance of disulfide linkages in maintaining the structure of C. cajan proteinase inhibitor.

Research paper thumbnail of Effect of trifluoroethanol on native and acid-induced states of glucose oxidase from Aspergillus niger

Biochemistry-moscow, 2010

We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.... more We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.6), and molten globule (pH 1.4) states of glucose oxidase (GOX) by circular dichroism and fluorescence spectroscopy. In the presence of 50% TFE, at pH 7.0 and 2.6, GOX exhibited a transition from native coiled-coil and acid unfolded state to non-associating alpha-helical state. Interestingly, at pH 1.4, 15% TFE induced the formation of beta-structured intermediate by loss of 1-anilino-8-naphthalenesulfonate binding site and almost all tertiary contacts. The beta-structured intermediate converted into open helical conformation on further addition of TFE.

Research paper thumbnail of Characterization of LEF4 ligand binding property and its role as part of baculoviral transcription machinery

Molecular and …, 2010

Late expression factor 4 (LEF4) is one of the four identified subunits of Autographa californica ... more Late expression factor 4 (LEF4) is one of the four identified subunits of Autographa californica nucleopolyhedrosis virus (AcNPV) encoded RNA polymerase that carries out transcription from viral late and very late promoters. This 464-amino acid baculovirus-encoded protein also harbors 5 0 mRNA capping activity that includes RNA 5 0 triphosphatase, nucleoside triphosphatase, and guanylyltransferase activities. Hydrolysis of 5 0 triphosphate RNA and free NTPs is metal ion dependent property of the protein. In the present communication, we describe the structural changes in the recombinant LEF4 protein following ligand binding. Metal ion binding causes some alteration in the conformation around aromatic amino acids whereas there is no effect on tryptophan fluorescence on GTP binding in absence and presence of metal ion. It is found that GTP and divalent cation cofactor produce some prominent changes in the secondary structure of the protein. Electrophoretic mobility shift assay (EMSA) shows that LEF4 is the probable factor that acts as anchor to dock the viral RNA polymerase on the very late polyhedrin promoter (Ppolh) facilitated by other factors.

Research paper thumbnail of Protease inhibitors: A panacea?

Journal of biochemical …, 2010

With the increasing evidence of protease involvement in several diseases, novel strategies for dr... more With the increasing evidence of protease involvement in several diseases, novel strategies for drug development involve the use of protease inhibitors (PIs). The local balance between protease inhibitors and proteases is an important determinant of the occurrence and progression of a particular disease. Hence, enzymes and their cognate inhibitors are finding their applications as diagnostic and prognostic markers. PIs are widely implicated for their use in host defense against infection, tissue repair and matrix production, blood coagulation, cancer, and they are, therefore, the current focus as therapeutic alternatives for major diseases such as AIDS and Alzheimer's diseases. This review is a brief summary of the varied role of protein protease inhibitors in controlling the activity of aberrant enzymes in several diseases afflicting mankind today. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:270–277, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20335

Research paper thumbnail of Effect of methyl mercury induced free radical stress on nucleic acids and protein: Implications on cognitive and motor functions

Indian Journal of Clinical …, 2006

Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest th... more Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest the adverse effect of low dose mercury, though the available literature is still silent on its mechanism. This study was therefore undertaken to probe the effect of low dose methyl mercury induced heavy metal toxicity on free radical stress and its impact on behaviour of male albino rats. Male albino rats were exposed to 1mg/kg body wt of methylmercury chloride for seven days, on day 8 they were tested for motor and memory functions. They were sacrificed later for biochemical estimations for rate of lipid peroxidation, nucleic acids, proteins in cerebrum, cerebellum and brain stem. There was an increase in the rate of lipid peroxidation showing methyl mercury induced free radical stress. The motor and memory functions demonstrated a clear decline, besides there was a lowering in the levels of nucleic acids and proteins as compared to controls. The results are important in view of recent reports that methyl mercury induced free radical stress results in early ageing and may serve as an initiating factor more specifically for neurodegenerative disorders like Alzeihemer's disease and dementias. The current findings support the notion that incorporating dietary antioxidants like curcumin, ascorbic acid and α-tocopherol in routine diet from early age may help combat the risk of developing such disorders in ensuing years.

Research paper thumbnail of Effect of detergents and hexafluoroisopropanol on the conformation of a non-helical and a helical plant protease inhibitor

International journal of biological macromolecules, 2005

We have earlier reported the purification of a non-helical proteinase inhibitor from Cajanus caja... more We have earlier reported the purification of a non-helical proteinase inhibitor from Cajanus cajan and a helical proteinase/amylase inhibitor from Phaseolus aureus. The effect of detergents, viz. sodium dodecyl sulfate (SDS), sodium deoxycholate (DOC) and 3-[(3-cholamidopropy) dimethylammonio]-1-propane sulfonate (CHAPS) and hexafluoroisopropanol on the conformation of these proteinaceous inhibitors was investigated using circular dichroism spectroscopy. The present report focuses on changes in the polypeptide backbone conformation with respect to induction of helical structure.SDS causes minimal changes in the tertiary as well as secondary structure of C. cajan proteinase inhibitor. In the presence of anionic bile salt, deoxycholate, minor changes in the far-UV CD spectrum were accompanied by loss in inhibitory activity while CHAPS did not affect the inhibitor function. As judged from the changes in circular dichroic curves ([Θ]MRW at 208 and 222 nm), the primarily disorganized polypeptide chain of C. cajan proteinase inhibitor was converted by 3,3,3,3′,3′,3′-hexafluoro-2-propanol (HFIP) into helical conformation.The P. aureus inhibitor showed increased helicity in the presence of SDS ([Θ]MRW at 208 nm) as well as sodium deoxycholate and CHAPS ([Θ]MRW at 222 nm). Fluorescence measurements show slight alterations in the emission intensities. HFIP caused a cooperative increase in α-helical secondary structure in the P. aureus inhibitor.

Research paper thumbnail of Expression, purification and ligand binding properties of the recombinant translation initiation factor (PeIF5B) from Pisum sativum

Molecular and cellular …, 2010

Gene encoding a novel translation initiation factor PeIF5B from Pisum sativum with sequence simil... more Gene encoding a novel translation initiation factor PeIF5B from Pisum sativum with sequence similarity to eIF5B from H. sapiens, D. melanogaster, S. cerevisiae as well as archaeal aIF5B from M. thermoautotrophicum was earlier reported by us. We now describe the expression and purification of 96 kDa recombinant PeIF5B (rPeIF5B) protein. Using fluorescence and circular dichroism spectra analyses, we show that Mg2+ binding does not lead to any change in PeIF5B aromatic amino acid micro-environment, whereas GTP binding induces significant changes in the local environment of the aromatic amino acids. However, the protein undergoes changes in secondary structure upon metal ion and nucleotide binding. Charged initiator tRNA binding to PeIF5B is found to be cofactor dependent. PeIF5B binds to GTP in vitro as evident from autoradiography. Based on homology modeling of the catalytic domain of PeIF5B, we could confirm the conformational changes in PeIF5B following ligand binding.

Research paper thumbnail of Isolation and Biochemical characterization of Protein Proteinase Inhibitors from Cajanus Cajan and Phaseolus Aureus

Research paper thumbnail of Identification and Characterization of Functional Intermediates of Stem Bromelain During Urea and Guanidine Hydrochloride Unfolding

Journal of Biochemistry, Dec 26, 2006

Research paper thumbnail of Bone morphogenic protein-7 (BMP-7) polymorphism: Susceptibility to cirrhosis and hepatocellular carcinoma after viral hepatitis in Egyptian patients

Clinical and Experimental Hepatology

Aim of the study: Bone morphogenic proteins (BMPs) have both inhibitory and stimulatory effects o... more Aim of the study: Bone morphogenic proteins (BMPs) have both inhibitory and stimulatory effects on growth of a tumor that depend on the type of cells, the dosage and the tumor microenvironment. We aimed to investigate the impact of the bone morphogenic protein-7 (BMP-7) single nucleotide polymorphism (SNP) rs230205 [A/G] on susceptibility to hepatocellular carcinoma (HCC) progression from liver cirrhosis after viral hepatitis infection in Egyptian patients. Material and methods: The amplification-refractory mutation system (ARMS)-polymerase chain reaction (PCR) method was used to genotype the rs230205 [A/G] SNP in 150 subjects (50 patients with post-hepatitis C or B cirrhosis, 50 HCC patients, and 50 controls). Expression level of BMP-7 protein was assessed using enzyme-linked immunosorbent assay (ELISA). Results: The results revealed insignificant changes in distribution of all genotypes/alleles of the BMP-7 rs230205 [A/G] SNP between cirrhotic patients, HCC patients and controls. The AA genotype and A allele could be considered risk factors for cirrhosis (OR = 1.75, 1.50) and HCC (OR = 2.19, 1.74), respectively. The AA genotype (95% CI: 0.45-6.79) and A allele (OR = 1.50, 95% CI: 0.77-2.93) may be viewed as cirrhosis risk factors based on group segregation. Additionally, the A allele, AG and AA genotypes and their combined ORs of 2.19 (95% CI: 0.58-8.23), 1.74 (95% CI: 0.90-3.37), and 1.70 (95% CI: 0.68-4.29) could all be risk factors for HCC. No genotype or allele could be regarded as a risk factor for progression of cirrhosis to HCC, according to OR values. Conclusions: The results showed no correlation between BMP-7 rs230205 [A/G] SNP and progression of cirrhosis to HCC. To confirm our findings, additional prospective large-scale research is required.

Research paper thumbnail of Acceptance, hesitancy, and refusal of coronavirus disease 2019 vaccine and associated factors in the population of Libya: A cross-sectional study

Libyan Journal of Medical Sciences

Research paper thumbnail of Trends in varicella epidemiology among an unvaccinated population: first results from Libya

Archives of Disease in Childhood

Research paper thumbnail of Clinical Characteristics of the First 100 Patients of COVID-19 in Tobruk, Libya: A Brief Report From Low-Resource Settings

Disaster Medicine and Public Health Preparedness

Objective:This study aims to report the clinical features of a cohort of patients with suspected ... more Objective:This study aims to report the clinical features of a cohort of patients with suspected coronavirus disease (COVID-19) from Tobruk, Libya, and reflect upon the diagnosis challenge in low-resource settings.Methods:A descriptive report of the first 100 patients with suspected COVID-19 who have visited the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and COVID-19 screening clinic at the National Centre for Disease Control in Tobruk, Libya.Results:The most common presenting symptoms were fever (90%), cough (89%), dyspnea (85%), sore throat (79%), fatigue (78%), headache (64%), loss of smell (52%), loss of taste (53%), loss of appetite (43%), nausea and vomiting (26%), diarrhea (22%), and rhinorrhea (16%); 51% of the patients had lymphocytopenia, whereas 13% had thrombocytopenia. Bilateral infiltrates were the most common radiologic finding on chest X-ray (76%), and COVID-19 IgM and/or IgG antibodies were detected in 80% of the patients, whereas only 37% of the p...

Research paper thumbnail of TB in eastern Libya: a decreasing trend in recent decades

The International Journal of Tuberculosis and Lung Disease

Research paper thumbnail of Hepatitis C Virus Infection in Eastern Libya: Efforts Needed to Improve HCV Testing and Linkage to Care in the Resource-Limited Setting

Tropical Medicine and Infectious Disease, 2022

Hepatitis C virus (HCV) is a significant public health problem, and the elimination of its infect... more Hepatitis C virus (HCV) is a significant public health problem, and the elimination of its infection by 2031 is a global goal. However, due to insufficient testing, lack of linkage to care (LTC) and treatment, Libya may be far from achieving this goal. This study aimed to explore HCV testing, the care and treatment of infected people, and to assess the burden of the infection among individuals who visited the main Medical Centre in Tobruk region, eastern Libya, for various medical and surgical conditions. A research team interviewed public health officials in Tobruk Medical Center, inspected available equipment, and obtained data available for people who were positive for antibodies to HCV (anti-HCV) as part of their routine pre-invasive procedures and pre-donation screening tests from January 2005 to April 2020. HCV antibody tests were positive for 612 cases out of 368,392 (0.17%). Of those who tested positive for anti-HCV antibodies, no one had followed up by RNA test for identify...

Research paper thumbnail of Antibiotic resistance patterns of urinary pathogens in outpatients and inpatients: A report from Eastern Libya

International Journal of Urological Nursing, 2021

Urinary tract infections (UTIs) are one of the most common infections and remain a public health ... more Urinary tract infections (UTIs) are one of the most common infections and remain a public health problem worldwide. Incidence of UTI‐causing pathogens and their antibiotic susceptibility are varied in different regions. To examine the frequency of UTIs among inpatients and outpatients at Tobruk Medical Centre, Eastern Libya to identify the UTIs most common causative agents, and to assess their resistance patterns to the commonly used antibiotics. A laboratory registry‐based retrospective survey included 25 388 urine samples obtained from symptomatic UTIs cases that attended the Tobruk Medical Centre in the period from January 2006 to December 2018. Antimicrobial susceptibility testing and bacterial identification were done as per the microbiology lab's standard operating procedure. The frequency of UTIs and their resistance patterns were examined in inpatients and outpatients. Out of 25 388 urine samples tested, 6838 (26.9%) showed growth of pathogens indicative of positive UTI....

Research paper thumbnail of Identification and characterization of functional intermediates of stem bromelain during urea and guanidine hydrochloride unfolding

Journal of biochemistry, 2007

By comparing changes in enzyme activity with changes in spectral features for stem bromelain (EC.... more By comparing changes in enzyme activity with changes in spectral features for stem bromelain (EC.3.4.22.32) in the absence and presence of urea, Guanidine hydrochloride and ethanol; four intermediate states could be identified: two activity-enhanced state obtained in the presence of 5 M urea and 2 M GnHCl, termed X and X', respectively, and a third, similarly active state closely resembling the native protein in the presence of 8-9 M urea, termed Y. The enhanced activity of these states is due to local conformational changes accompanied by increased dynamics in the active site. Further, the enzyme does not lose its activity after substantial tertiary structure changes in 8-9 M urea (Y state), suggesting that active site containing domain is more resistant to chemical denaturation than the other structural domain. This makes stem bromelain and in general cysteine proteases an exception to the hypothesis that active site is the most labile part of enzyme.

Research paper thumbnail of Methylmercury

Research paper thumbnail of Effect of trifluoroethanol on native and acid-induced states of glucose oxidase from Aspergillus niger

Biochemistry (Moscow), 2010

We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.... more We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.6), and molten globule (pH 1.4) states of glucose oxidase (GOX) by circular dichroism and fluorescence spectroscopy. In the presence of 50% TFE, at pH 7.0 and 2.6, GOX exhibited a transition from native coiled-coil and acid unfolded state to non-associating alpha-helical state. Interestingly, at pH 1.4, 15% TFE induced the formation of beta-structured intermediate by loss of 1-anilino-8-naphthalenesulfonate binding site and almost all tertiary contacts. The beta-structured intermediate converted into open helical conformation on further addition of TFE.

Research paper thumbnail of Low SARS-CoV-2 Antibodies in Blood Donors After the First 6 Months of COVID-19 Epidemic in the Tobruk Region, Eastern Libya

Disaster Medicine and Public Health Preparedness

Coronavirus disease 2019 (COVID-19) is primarily a respiratory virus and there is no evidence of ... more Coronavirus disease 2019 (COVID-19) is primarily a respiratory virus and there is no evidence of transfusion transmission for COVID-19;1, 2 however, estimation of the seroprevalence rate of antibodies to severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) in blood donors’ population reflects the progression of the epidemic in the region. It is unclear how many people have contracted the virus since only symptomatic cases have been registered. For this reason, and as a part of the National Centre for Disease Control preparedness plan to combat the spread of the COVID-19 infection in the Tobruk region, eastern Libya, we conducted a cross-sectional study between January 15 to February 15, 2021, six months after the identification of the first confirmed COVID-19 case in the region on 23 July 2020. 3

Research paper thumbnail of Spectroscopic analysis of thermal denaturation of Cajanus cajan proteinase inhibitor at neutral and acidic pH by circular dichroism

International Journal of Biological Macromolecules, 2005

The conformational changes accompanying thermal denaturation under neutral, acidic and reducing c... more The conformational changes accompanying thermal denaturation under neutral, acidic and reducing conditions of Cajanus cajan proteinase inhibitor were investigated using near- and far-ultraviolet circular dichroism (CD) spectroscopy. The protein inhibitor shows a reversible N ↔ D transition at neutral pH with a Tm approximately equal to 63 °C. The negative CD band intensities at 200 nm (far-UV) and near about 280 nm (near-UV) decrease as a result of thermal stress. The effect is more pronounced at low pH and in the presence of dithiothreitol. Only partial reversibility is observed under acidic conditions. Significant changes in the near- as well as far-ultraviolet CD spectrum are observed in the presence of dithiothreitol suggestive of the importance of disulfide linkages in maintaining the structure of C. cajan proteinase inhibitor.

Research paper thumbnail of Effect of trifluoroethanol on native and acid-induced states of glucose oxidase from Aspergillus niger

Biochemistry-moscow, 2010

We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.... more We have studied the effect of trifluoroethanol (TFE) on the native (pH 7.0), acid unfolded (pH 2.6), and molten globule (pH 1.4) states of glucose oxidase (GOX) by circular dichroism and fluorescence spectroscopy. In the presence of 50% TFE, at pH 7.0 and 2.6, GOX exhibited a transition from native coiled-coil and acid unfolded state to non-associating alpha-helical state. Interestingly, at pH 1.4, 15% TFE induced the formation of beta-structured intermediate by loss of 1-anilino-8-naphthalenesulfonate binding site and almost all tertiary contacts. The beta-structured intermediate converted into open helical conformation on further addition of TFE.

Research paper thumbnail of Characterization of LEF4 ligand binding property and its role as part of baculoviral transcription machinery

Molecular and …, 2010

Late expression factor 4 (LEF4) is one of the four identified subunits of Autographa californica ... more Late expression factor 4 (LEF4) is one of the four identified subunits of Autographa californica nucleopolyhedrosis virus (AcNPV) encoded RNA polymerase that carries out transcription from viral late and very late promoters. This 464-amino acid baculovirus-encoded protein also harbors 5 0 mRNA capping activity that includes RNA 5 0 triphosphatase, nucleoside triphosphatase, and guanylyltransferase activities. Hydrolysis of 5 0 triphosphate RNA and free NTPs is metal ion dependent property of the protein. In the present communication, we describe the structural changes in the recombinant LEF4 protein following ligand binding. Metal ion binding causes some alteration in the conformation around aromatic amino acids whereas there is no effect on tryptophan fluorescence on GTP binding in absence and presence of metal ion. It is found that GTP and divalent cation cofactor produce some prominent changes in the secondary structure of the protein. Electrophoretic mobility shift assay (EMSA) shows that LEF4 is the probable factor that acts as anchor to dock the viral RNA polymerase on the very late polyhedrin promoter (Ppolh) facilitated by other factors.

Research paper thumbnail of Protease inhibitors: A panacea?

Journal of biochemical …, 2010

With the increasing evidence of protease involvement in several diseases, novel strategies for dr... more With the increasing evidence of protease involvement in several diseases, novel strategies for drug development involve the use of protease inhibitors (PIs). The local balance between protease inhibitors and proteases is an important determinant of the occurrence and progression of a particular disease. Hence, enzymes and their cognate inhibitors are finding their applications as diagnostic and prognostic markers. PIs are widely implicated for their use in host defense against infection, tissue repair and matrix production, blood coagulation, cancer, and they are, therefore, the current focus as therapeutic alternatives for major diseases such as AIDS and Alzheimer's diseases. This review is a brief summary of the varied role of protein protease inhibitors in controlling the activity of aberrant enzymes in several diseases afflicting mankind today. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:270–277, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20335

Research paper thumbnail of Effect of methyl mercury induced free radical stress on nucleic acids and protein: Implications on cognitive and motor functions

Indian Journal of Clinical …, 2006

Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest th... more Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest the adverse effect of low dose mercury, though the available literature is still silent on its mechanism. This study was therefore undertaken to probe the effect of low dose methyl mercury induced heavy metal toxicity on free radical stress and its impact on behaviour of male albino rats. Male albino rats were exposed to 1mg/kg body wt of methylmercury chloride for seven days, on day 8 they were tested for motor and memory functions. They were sacrificed later for biochemical estimations for rate of lipid peroxidation, nucleic acids, proteins in cerebrum, cerebellum and brain stem. There was an increase in the rate of lipid peroxidation showing methyl mercury induced free radical stress. The motor and memory functions demonstrated a clear decline, besides there was a lowering in the levels of nucleic acids and proteins as compared to controls. The results are important in view of recent reports that methyl mercury induced free radical stress results in early ageing and may serve as an initiating factor more specifically for neurodegenerative disorders like Alzeihemer's disease and dementias. The current findings support the notion that incorporating dietary antioxidants like curcumin, ascorbic acid and α-tocopherol in routine diet from early age may help combat the risk of developing such disorders in ensuing years.

Research paper thumbnail of Effect of detergents and hexafluoroisopropanol on the conformation of a non-helical and a helical plant protease inhibitor

International journal of biological macromolecules, 2005

We have earlier reported the purification of a non-helical proteinase inhibitor from Cajanus caja... more We have earlier reported the purification of a non-helical proteinase inhibitor from Cajanus cajan and a helical proteinase/amylase inhibitor from Phaseolus aureus. The effect of detergents, viz. sodium dodecyl sulfate (SDS), sodium deoxycholate (DOC) and 3-[(3-cholamidopropy) dimethylammonio]-1-propane sulfonate (CHAPS) and hexafluoroisopropanol on the conformation of these proteinaceous inhibitors was investigated using circular dichroism spectroscopy. The present report focuses on changes in the polypeptide backbone conformation with respect to induction of helical structure.SDS causes minimal changes in the tertiary as well as secondary structure of C. cajan proteinase inhibitor. In the presence of anionic bile salt, deoxycholate, minor changes in the far-UV CD spectrum were accompanied by loss in inhibitory activity while CHAPS did not affect the inhibitor function. As judged from the changes in circular dichroic curves ([Θ]MRW at 208 and 222 nm), the primarily disorganized polypeptide chain of C. cajan proteinase inhibitor was converted by 3,3,3,3′,3′,3′-hexafluoro-2-propanol (HFIP) into helical conformation.The P. aureus inhibitor showed increased helicity in the presence of SDS ([Θ]MRW at 208 nm) as well as sodium deoxycholate and CHAPS ([Θ]MRW at 222 nm). Fluorescence measurements show slight alterations in the emission intensities. HFIP caused a cooperative increase in α-helical secondary structure in the P. aureus inhibitor.

Research paper thumbnail of Expression, purification and ligand binding properties of the recombinant translation initiation factor (PeIF5B) from Pisum sativum

Molecular and cellular …, 2010

Gene encoding a novel translation initiation factor PeIF5B from Pisum sativum with sequence simil... more Gene encoding a novel translation initiation factor PeIF5B from Pisum sativum with sequence similarity to eIF5B from H. sapiens, D. melanogaster, S. cerevisiae as well as archaeal aIF5B from M. thermoautotrophicum was earlier reported by us. We now describe the expression and purification of 96 kDa recombinant PeIF5B (rPeIF5B) protein. Using fluorescence and circular dichroism spectra analyses, we show that Mg2+ binding does not lead to any change in PeIF5B aromatic amino acid micro-environment, whereas GTP binding induces significant changes in the local environment of the aromatic amino acids. However, the protein undergoes changes in secondary structure upon metal ion and nucleotide binding. Charged initiator tRNA binding to PeIF5B is found to be cofactor dependent. PeIF5B binds to GTP in vitro as evident from autoradiography. Based on homology modeling of the catalytic domain of PeIF5B, we could confirm the conformational changes in PeIF5B following ligand binding.