Mahesh Kumar - Academia.edu (original) (raw)
Papers by Mahesh Kumar
Synlett, 2001
© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journa... more © Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or ...
Synthesis, 2001
In recent years, lithium perchlorate in diethyl ether has received considerable attention as a po... more In recent years, lithium perchlorate in diethyl ether has received considerable attention as a powerful reaction medium for effecting various organic transformations [11] [12] such as cycloaddition reactions, sigmatropic rearrangements, ring-opening reactions of epoxides, glycosidation ...
ChemInform, May 25, 2010
2001 indole derivatives, isoindole derivatives indole derivatives, isoindole derivatives R 0140 3... more 2001 indole derivatives, isoindole derivatives indole derivatives, isoindole derivatives R 0140 33-128 Lithium Perchlorate Catalyzed Reactions of Indoles: An Expeditious Synthesis of Bis(indolyl)methanes.-15 Bis(indolyl)methanes such as (III) and (V) are prepared by LiClO 4-catalyzed electrophilic substitution reaction of indole with aldehydes such as (II) or ketones such as (IV). Instead of Et 2 O, acetonitrile can be used as solvent.-(YADAV, JHILLU S.; REDDY,
Sugar Tech, 2012
Storage behaviour of cubical jaggery samples stored in linear density polyethylene (LDPE), poly p... more Storage behaviour of cubical jaggery samples stored in linear density polyethylene (LDPE), poly propylene (PP) and polyethylene terephthalate (PET) films under 100 % nitrogen was investigated for a period of 8 months (February-September). Jute bag was taken as control. The change in quality characteristics such as moisture content, colour, hardness, reducing sugar and total phenols was determined at an interval of one month. The experimental data showed that jaggery moisture increased from 10.53 to 15.49 (wb) in jute bag storage while it decreased to 9.45, 9.31 and 9.63 in LDPE, PET and PP respectively. Similarly the L value of colour measurement showed a decreasing trend in all type of storage which indicated that jaggery became darker during storage. The reducing sugar increased in all storage materials during storage. The increase was maximum for jute bag (25.81) followed by PP (14.99). Hardness decreased from 360 to 67.42, 64.56, 97.36 and 1.97 newtons (N) in LDPE, PET, PP and jute bag, respectively. Good keeping quality can be maintained in polymeric films with nitrogen flushing. Overall performance of PET film was best as it showed less reduction in quality parameters during storage.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Experiments were conducted to examine the individual and combined effect of two different electro... more Experiments were conducted to examine the individual and combined effect of two different electromagnetic energies, i.e., gamma ray viz 0.1, 0.5 and 1 kGy and static magnetic field (50 mT for 1 h) and their combination (0.5 kGy ? 50 mT) on the shelf life of tomato and evaluates the biochemical attributes that influence the fruit ripening and fruit quality. Magnetic field application either alone or in combination with gamma irradiation was not effective in delaying the ripening process. Gamma ray exposed fruits at 0.5 and 1 kGy showed an extended shelf life due to delayed fruit ripening and reduced lycopene synthesis and ethylene production. Efficient ROS scavenging ability and consequent reduction in oxidative damage in the irradiated treatment may cause favorable biochemical changes to facilitate delayed ripening of the tomato fruits.
Synthetic Communications, 2002
Small Ruminant Research, 2002
Of eight clinically endemic goitrous goats procured locally, six were treated with sodium thyroxi... more Of eight clinically endemic goitrous goats procured locally, six were treated with sodium thyroxine at 0.2 mg per day per goat orally for 100 days. Histopathology of heart in two untreated and two treated goats revealed extensive fatty vacuolization of myocardial ®bers in the former group, which was replaced by granularity in the latter group. There was higher plasma total cholesterol and lipids in goitrous goats (
Small Ruminant Research, 2006
To know the functional status of immune system, 24 clinically affected goitrous goat were procure... more To know the functional status of immune system, 24 clinically affected goitrous goat were procured from an endemic area and divided into three groups of A, B and C of eight each. Group A and B goats were treated with colloidal iodine at the rate of 0.1mg/kg body weight×100 days and synthetic sodium thyroxine at the rate of 0.2mg/day orally
Molecular Cytogenetics, 2014
Molecular Crystals and Liquid Crystals, 2013
ABSTRACT The title compound, C22H19N3O2, was prepared from the three-component reaction. The stru... more ABSTRACT The title compound, C22H19N3O2, was prepared from the three-component reaction. The structure of the title compound was established by single-crystal X-ray diffraction. The molecular structure shows that the phenyl ring is not coplanar with the pyrimidine ring. The torsion angle between the phenyl ring and pyrimidine ring is 147.01(15)°. The glide related molecules form one-dimensional corrugated tape-like structure via C–H···O hydrogen bonds along the crystallographic b-axis. These one-dimensional layers stack along the a-axis and form a corrugated layered structure and these layers are further stabilized by the weak C–H···π interactions. Also, it was found that the pyrazole moiety and p-toluyl groups of glide-related molecules are stacked through π···π interactions.
Journal of Applied Animal Research, 1995
Changes in urine in experimental ethylene glycol intoxication in cow calves. J. Appl. Anim Appare... more Changes in urine in experimental ethylene glycol intoxication in cow calves. J. Appl. Anim Apparently healthy male crossbred cow calves (18) aged 4-5 months were divided into 3 equal groups. Acute and sub-acute nephrotoxicity was developed in calves of groups A and B by giving ethylene glycol orally @ 12 ml and 7.5mllkg bwt respectively, for 2 days continuously. Microscopic examination of urine samples revealed presence of calcium oxalate and triple phosphate crystals, casts, few pus cells, erythrocytes and epithelial cells. The p H of urine was reduced in calves of both the groups. Urea and creatinine levels were increased from day 1 to 3 in calves of group A whereas in group B, these increased from day 1 to 20. Activity of GGT increased in urine samples from day 1 to 3 in group A and from day 1 to 20 with maximum increase on day 5 in group B.
Journal of Alloys and Compounds, 2011
Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (Zn... more Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (ZnO:SnO 2 ; 100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZTO films were annealed at 450 • C in vacuum. These films were characterized to study the effect of annealing and addition of SnO 2 concentration on the structural, chemical and electrical properties. The XRD analysis indicates that crystallization of the ZTO films strongly depends on the concentration of SnO 2 and post annealing where annealed films showed polycrystalline nature. Atomic force microscopy (AFM) images manifest the surface morphology of these ZTO thin films. The XPS core level spectra of Zn(2p), O(1s) and Sn(3d) have been deconvoluted into their Gaussian component to evaluate the chemical changes, while valence band spectra reveal the electronic structures of these films. A small shift in Zn(2p) and Sn(3d) core level towards higher binding energy and O(1s) core level towards lower binding energy have been observed. The minimum electrical resistivity (≈ 3.69 × 10 −2-cm), maximum carrier concentration (n ≈ 3.26 × 10 19 cm −3) and Hall mobility (≈ 5.2 cm 2 v −1 s −1) were obtained for as-prepared ZTO (50:50) film thereafter move towards lowest resistivity (≈ 1.12 × 10 −3-cm), highest carrier concentration (n ≈ 2.96 × 10 20 cm −3) and mobility (≈ 18.8 cm 2 v −1 s −1) for annealed ZTO (50:50) thin film.
Communications in Soil Science and Plant Analysis, 2005
Abstract The chemical diagnosis of nutritional status of Bael (Aegle marmelos Correa) tree by lea... more Abstract The chemical diagnosis of nutritional status of Bael (Aegle marmelos Correa) tree by leaf analysis was done to study the effect of leaf age and leaf position on foliar nutrient composition of Bael. The results showed that leaf age has significant influence on leaf mineral content, whereas the position of leaf on shoot did not have any significant effect. Interactions between leaf age and position were found to be significant for nitrogen, boron and iron content. In general, stability in level of nitrogen (N), phosphorus (P), and potassium (K) contents was observed in November–December (6‐ to 7‐month‐old leaves) and calcium (Ca) and magnesium (Mg) showed their stability in 2‐to 3‐month‐old leaves (July–August). The contents of boron (B), manganese (Mn), copper (Cu), and zinc (Zn) were found stabilized in September–October (3‐ to 4‐month‐old leaves), indicating their suitability for sampling in Bael.
Colloid and Polymer Science, 2010
Page 1. ORIGINAL CONTRIBUTION Role of surface modification of colloidal CdSe quantum dots on the ... more Page 1. ORIGINAL CONTRIBUTION Role of surface modification of colloidal CdSe quantum dots on the properties of hybrid organicinorganic nanocomposites Umesh Kumar & Kusum Kumari & Shailesh N. Sharma & Mahesh Kumar & VD Vankar & Rita Kakkar & Vikram Kumar ...
Chem. Commun., 2012
Unless stated otherwise, reactions were monitored by thin layer chromatography (TLC) on silica ge... more Unless stated otherwise, reactions were monitored by thin layer chromatography (TLC) on silica gel plates (60 F 254), visualizing with ultraviolet light or iodine spray. Column chromatography was performed on silica gel (60-120 mesh) using distilled petroleum ether and ethyl acetate. 1 H and 13 C NMR spectra were determined in CDCl 3 /DMSO-d 6 solution using 400 and 100 MHz spectrometers, respectively. Proton chemical shifts (δ) are relative to tetramethylsilane (TMS, δ = 0.0) as internal standard and expressed in parts per million. Spin multiplicities are given as s (singlet), d (doublet), t (triplet), and m (multiplet) as well as b (broad). Coupling constants (J) are given in hertz. Infrared spectra were recorded on a FTIR spectrometer. Melting points were determined by using a Buchi melting point B-540 apparatus. MS spectra were obtained on a mass spectrometer. HRMS was determined using waters LCT premier XETOF ARE-047 apparatus. General procedure for the preparation of compound 4 (and 5) A mixture of 3-amino-1H-pyrazole-4-carboxylic acid ethyl ester (1.0 mmol), an appropriate aldehyde (1 mmol) and a terminal alkyne (1 mmol) in acetic acid (5 mL) was stirred at 25 °C for 10 min. To this clear solution was added triflic acid (10 mol %) and the mixture was heated to 100-110°C. The reaction mixture was then stirred at same temperature for 2 h. After completion of the reaction the mixture was cooled to room temperature, poured into ethyl acetate (25 mL) and washed with brine solution (2 x 15 mL) followed by 10% NaHCO 3 solution (2 x 15 mL). The organic layer was collected, dried over anhydrous Na 2 SO 4 and concentrated. The residue isolated was purified by column chromatography using petroleum ether-EtOAc to give the desired product. Ethyl 5-phenyl-7-(p-tolyl)pyrazolo[1,5-a]pyrimidine-3-carboxylate (4a)
Biochimica et Biophysica Acta (BBA) - General Subjects, 2013
Background: It is known that tandem domains of enzymes can carry out catalysis independently or b... more Background: It is known that tandem domains of enzymes can carry out catalysis independently or by collaboration. In the case of cysteine proteases, domain sequestration abolishes catalysis because the active site residues are distributed in both domains. The validity of this argument is tested here by using isolated human ribosomal protein S4, which has been recently identified as an unorthodox cysteine protease. Methods: Cleavage of the peptide substrate Z-FR↓-AMC catalyzed by recombinant C-terminal domain of human S4 (CHS4) is studied by fluorescence-monitored steady-state and stopped-flow kinetic methods. Proteolysis and autoproteolysis were analyzed by electrophoresis. Results: The CHS4 domain comprised of sequence residues 116-263 has been cloned and ovreexpressed in Escherichia coli. The purified domain is enzymatically active. Barring minor differences, steady-state kinetic parameters for catalysis by CHS4 are very similar to those for full-length human S4. Further, stopped-flow transient kinetics of pre-steady-state substrate binding shows that the catalytic mechanism for both full-length S4 and CHS4 obeys the Michaelis-Menten model adequately. Consideration of the evolutionary domain organization of the S4e family of ribosomal proteins indicates that the central domain (residues 94-170) within CHS4 is indispensable. Conclusion: The C-terminal domain can carry out catalysis independently and as efficiently as the full-length human S4 does. Significance: Localization of the enzyme function in the C-terminal domain of human S4 provides the only example of a cysteine endoprotease where substrate-mediated intramolecular domain interaction is irrelevant for catalytic activity.
Applied Surface Science, 2010
The effect of substrate bias on X-ray photoelectron spectroscopy (XPS) study of nitrogen incorpor... more The effect of substrate bias on X-ray photoelectron spectroscopy (XPS) study of nitrogen incorporated amorphous carbon (a-C:N) films embedded with nanoparticles deposited by filtered cathodic jet carbon arc technique is discussed. High resolution transmission electron microscope exhibited initially the amorphous structure but on closer examination the film was constituted of amorphous phase with the nanoparticle embedded in the amorphous matrix.
Acta Crystallographica Section E Structure Reports Online, 2012
In the title compound, C17H19NO2S2, the 2H-chromene ring system is almost planar, with a maximum ... more In the title compound, C17H19NO2S2, the 2H-chromene ring system is almost planar, with a maximum deviation of 0.044 (2) Å, and the pyrrolidine ring adopts an envelope conformation. The dihedral angle between the 2H-chromene system and the planar part of the pyrrolidine ring is 83.65 (8)°. A weak intramolecular C—H...S hydrogen bond occurs. The crystal structure features C—H...O hydrogen bonds and π–π interactions, with a centroid–centroid distance of 3.5728 (16) Å.
Acta Crystallographica Section E Structure Reports Online, 2012
Synlett, 2001
© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journa... more © Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or ...
Synthesis, 2001
In recent years, lithium perchlorate in diethyl ether has received considerable attention as a po... more In recent years, lithium perchlorate in diethyl ether has received considerable attention as a powerful reaction medium for effecting various organic transformations [11] [12] such as cycloaddition reactions, sigmatropic rearrangements, ring-opening reactions of epoxides, glycosidation ...
ChemInform, May 25, 2010
2001 indole derivatives, isoindole derivatives indole derivatives, isoindole derivatives R 0140 3... more 2001 indole derivatives, isoindole derivatives indole derivatives, isoindole derivatives R 0140 33-128 Lithium Perchlorate Catalyzed Reactions of Indoles: An Expeditious Synthesis of Bis(indolyl)methanes.-15 Bis(indolyl)methanes such as (III) and (V) are prepared by LiClO 4-catalyzed electrophilic substitution reaction of indole with aldehydes such as (II) or ketones such as (IV). Instead of Et 2 O, acetonitrile can be used as solvent.-(YADAV, JHILLU S.; REDDY,
Sugar Tech, 2012
Storage behaviour of cubical jaggery samples stored in linear density polyethylene (LDPE), poly p... more Storage behaviour of cubical jaggery samples stored in linear density polyethylene (LDPE), poly propylene (PP) and polyethylene terephthalate (PET) films under 100 % nitrogen was investigated for a period of 8 months (February-September). Jute bag was taken as control. The change in quality characteristics such as moisture content, colour, hardness, reducing sugar and total phenols was determined at an interval of one month. The experimental data showed that jaggery moisture increased from 10.53 to 15.49 (wb) in jute bag storage while it decreased to 9.45, 9.31 and 9.63 in LDPE, PET and PP respectively. Similarly the L value of colour measurement showed a decreasing trend in all type of storage which indicated that jaggery became darker during storage. The reducing sugar increased in all storage materials during storage. The increase was maximum for jute bag (25.81) followed by PP (14.99). Hardness decreased from 360 to 67.42, 64.56, 97.36 and 1.97 newtons (N) in LDPE, PET, PP and jute bag, respectively. Good keeping quality can be maintained in polymeric films with nitrogen flushing. Overall performance of PET film was best as it showed less reduction in quality parameters during storage.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Experiments were conducted to examine the individual and combined effect of two different electro... more Experiments were conducted to examine the individual and combined effect of two different electromagnetic energies, i.e., gamma ray viz 0.1, 0.5 and 1 kGy and static magnetic field (50 mT for 1 h) and their combination (0.5 kGy ? 50 mT) on the shelf life of tomato and evaluates the biochemical attributes that influence the fruit ripening and fruit quality. Magnetic field application either alone or in combination with gamma irradiation was not effective in delaying the ripening process. Gamma ray exposed fruits at 0.5 and 1 kGy showed an extended shelf life due to delayed fruit ripening and reduced lycopene synthesis and ethylene production. Efficient ROS scavenging ability and consequent reduction in oxidative damage in the irradiated treatment may cause favorable biochemical changes to facilitate delayed ripening of the tomato fruits.
Synthetic Communications, 2002
Small Ruminant Research, 2002
Of eight clinically endemic goitrous goats procured locally, six were treated with sodium thyroxi... more Of eight clinically endemic goitrous goats procured locally, six were treated with sodium thyroxine at 0.2 mg per day per goat orally for 100 days. Histopathology of heart in two untreated and two treated goats revealed extensive fatty vacuolization of myocardial ®bers in the former group, which was replaced by granularity in the latter group. There was higher plasma total cholesterol and lipids in goitrous goats (
Small Ruminant Research, 2006
To know the functional status of immune system, 24 clinically affected goitrous goat were procure... more To know the functional status of immune system, 24 clinically affected goitrous goat were procured from an endemic area and divided into three groups of A, B and C of eight each. Group A and B goats were treated with colloidal iodine at the rate of 0.1mg/kg body weight×100 days and synthetic sodium thyroxine at the rate of 0.2mg/day orally
Molecular Cytogenetics, 2014
Molecular Crystals and Liquid Crystals, 2013
ABSTRACT The title compound, C22H19N3O2, was prepared from the three-component reaction. The stru... more ABSTRACT The title compound, C22H19N3O2, was prepared from the three-component reaction. The structure of the title compound was established by single-crystal X-ray diffraction. The molecular structure shows that the phenyl ring is not coplanar with the pyrimidine ring. The torsion angle between the phenyl ring and pyrimidine ring is 147.01(15)°. The glide related molecules form one-dimensional corrugated tape-like structure via C–H···O hydrogen bonds along the crystallographic b-axis. These one-dimensional layers stack along the a-axis and form a corrugated layered structure and these layers are further stabilized by the weak C–H···π interactions. Also, it was found that the pyrazole moiety and p-toluyl groups of glide-related molecules are stacked through π···π interactions.
Journal of Applied Animal Research, 1995
Changes in urine in experimental ethylene glycol intoxication in cow calves. J. Appl. Anim Appare... more Changes in urine in experimental ethylene glycol intoxication in cow calves. J. Appl. Anim Apparently healthy male crossbred cow calves (18) aged 4-5 months were divided into 3 equal groups. Acute and sub-acute nephrotoxicity was developed in calves of groups A and B by giving ethylene glycol orally @ 12 ml and 7.5mllkg bwt respectively, for 2 days continuously. Microscopic examination of urine samples revealed presence of calcium oxalate and triple phosphate crystals, casts, few pus cells, erythrocytes and epithelial cells. The p H of urine was reduced in calves of both the groups. Urea and creatinine levels were increased from day 1 to 3 in calves of group A whereas in group B, these increased from day 1 to 20. Activity of GGT increased in urine samples from day 1 to 3 in group A and from day 1 to 20 with maximum increase on day 5 in group B.
Journal of Alloys and Compounds, 2011
Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (Zn... more Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (ZnO:SnO 2 ; 100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZTO films were annealed at 450 • C in vacuum. These films were characterized to study the effect of annealing and addition of SnO 2 concentration on the structural, chemical and electrical properties. The XRD analysis indicates that crystallization of the ZTO films strongly depends on the concentration of SnO 2 and post annealing where annealed films showed polycrystalline nature. Atomic force microscopy (AFM) images manifest the surface morphology of these ZTO thin films. The XPS core level spectra of Zn(2p), O(1s) and Sn(3d) have been deconvoluted into their Gaussian component to evaluate the chemical changes, while valence band spectra reveal the electronic structures of these films. A small shift in Zn(2p) and Sn(3d) core level towards higher binding energy and O(1s) core level towards lower binding energy have been observed. The minimum electrical resistivity (≈ 3.69 × 10 −2-cm), maximum carrier concentration (n ≈ 3.26 × 10 19 cm −3) and Hall mobility (≈ 5.2 cm 2 v −1 s −1) were obtained for as-prepared ZTO (50:50) film thereafter move towards lowest resistivity (≈ 1.12 × 10 −3-cm), highest carrier concentration (n ≈ 2.96 × 10 20 cm −3) and mobility (≈ 18.8 cm 2 v −1 s −1) for annealed ZTO (50:50) thin film.
Communications in Soil Science and Plant Analysis, 2005
Abstract The chemical diagnosis of nutritional status of Bael (Aegle marmelos Correa) tree by lea... more Abstract The chemical diagnosis of nutritional status of Bael (Aegle marmelos Correa) tree by leaf analysis was done to study the effect of leaf age and leaf position on foliar nutrient composition of Bael. The results showed that leaf age has significant influence on leaf mineral content, whereas the position of leaf on shoot did not have any significant effect. Interactions between leaf age and position were found to be significant for nitrogen, boron and iron content. In general, stability in level of nitrogen (N), phosphorus (P), and potassium (K) contents was observed in November–December (6‐ to 7‐month‐old leaves) and calcium (Ca) and magnesium (Mg) showed their stability in 2‐to 3‐month‐old leaves (July–August). The contents of boron (B), manganese (Mn), copper (Cu), and zinc (Zn) were found stabilized in September–October (3‐ to 4‐month‐old leaves), indicating their suitability for sampling in Bael.
Colloid and Polymer Science, 2010
Page 1. ORIGINAL CONTRIBUTION Role of surface modification of colloidal CdSe quantum dots on the ... more Page 1. ORIGINAL CONTRIBUTION Role of surface modification of colloidal CdSe quantum dots on the properties of hybrid organicinorganic nanocomposites Umesh Kumar & Kusum Kumari & Shailesh N. Sharma & Mahesh Kumar & VD Vankar & Rita Kakkar & Vikram Kumar ...
Chem. Commun., 2012
Unless stated otherwise, reactions were monitored by thin layer chromatography (TLC) on silica ge... more Unless stated otherwise, reactions were monitored by thin layer chromatography (TLC) on silica gel plates (60 F 254), visualizing with ultraviolet light or iodine spray. Column chromatography was performed on silica gel (60-120 mesh) using distilled petroleum ether and ethyl acetate. 1 H and 13 C NMR spectra were determined in CDCl 3 /DMSO-d 6 solution using 400 and 100 MHz spectrometers, respectively. Proton chemical shifts (δ) are relative to tetramethylsilane (TMS, δ = 0.0) as internal standard and expressed in parts per million. Spin multiplicities are given as s (singlet), d (doublet), t (triplet), and m (multiplet) as well as b (broad). Coupling constants (J) are given in hertz. Infrared spectra were recorded on a FTIR spectrometer. Melting points were determined by using a Buchi melting point B-540 apparatus. MS spectra were obtained on a mass spectrometer. HRMS was determined using waters LCT premier XETOF ARE-047 apparatus. General procedure for the preparation of compound 4 (and 5) A mixture of 3-amino-1H-pyrazole-4-carboxylic acid ethyl ester (1.0 mmol), an appropriate aldehyde (1 mmol) and a terminal alkyne (1 mmol) in acetic acid (5 mL) was stirred at 25 °C for 10 min. To this clear solution was added triflic acid (10 mol %) and the mixture was heated to 100-110°C. The reaction mixture was then stirred at same temperature for 2 h. After completion of the reaction the mixture was cooled to room temperature, poured into ethyl acetate (25 mL) and washed with brine solution (2 x 15 mL) followed by 10% NaHCO 3 solution (2 x 15 mL). The organic layer was collected, dried over anhydrous Na 2 SO 4 and concentrated. The residue isolated was purified by column chromatography using petroleum ether-EtOAc to give the desired product. Ethyl 5-phenyl-7-(p-tolyl)pyrazolo[1,5-a]pyrimidine-3-carboxylate (4a)
Biochimica et Biophysica Acta (BBA) - General Subjects, 2013
Background: It is known that tandem domains of enzymes can carry out catalysis independently or b... more Background: It is known that tandem domains of enzymes can carry out catalysis independently or by collaboration. In the case of cysteine proteases, domain sequestration abolishes catalysis because the active site residues are distributed in both domains. The validity of this argument is tested here by using isolated human ribosomal protein S4, which has been recently identified as an unorthodox cysteine protease. Methods: Cleavage of the peptide substrate Z-FR↓-AMC catalyzed by recombinant C-terminal domain of human S4 (CHS4) is studied by fluorescence-monitored steady-state and stopped-flow kinetic methods. Proteolysis and autoproteolysis were analyzed by electrophoresis. Results: The CHS4 domain comprised of sequence residues 116-263 has been cloned and ovreexpressed in Escherichia coli. The purified domain is enzymatically active. Barring minor differences, steady-state kinetic parameters for catalysis by CHS4 are very similar to those for full-length human S4. Further, stopped-flow transient kinetics of pre-steady-state substrate binding shows that the catalytic mechanism for both full-length S4 and CHS4 obeys the Michaelis-Menten model adequately. Consideration of the evolutionary domain organization of the S4e family of ribosomal proteins indicates that the central domain (residues 94-170) within CHS4 is indispensable. Conclusion: The C-terminal domain can carry out catalysis independently and as efficiently as the full-length human S4 does. Significance: Localization of the enzyme function in the C-terminal domain of human S4 provides the only example of a cysteine endoprotease where substrate-mediated intramolecular domain interaction is irrelevant for catalytic activity.
Applied Surface Science, 2010
The effect of substrate bias on X-ray photoelectron spectroscopy (XPS) study of nitrogen incorpor... more The effect of substrate bias on X-ray photoelectron spectroscopy (XPS) study of nitrogen incorporated amorphous carbon (a-C:N) films embedded with nanoparticles deposited by filtered cathodic jet carbon arc technique is discussed. High resolution transmission electron microscope exhibited initially the amorphous structure but on closer examination the film was constituted of amorphous phase with the nanoparticle embedded in the amorphous matrix.
Acta Crystallographica Section E Structure Reports Online, 2012
In the title compound, C17H19NO2S2, the 2H-chromene ring system is almost planar, with a maximum ... more In the title compound, C17H19NO2S2, the 2H-chromene ring system is almost planar, with a maximum deviation of 0.044 (2) Å, and the pyrrolidine ring adopts an envelope conformation. The dihedral angle between the 2H-chromene system and the planar part of the pyrrolidine ring is 83.65 (8)°. A weak intramolecular C—H...S hydrogen bond occurs. The crystal structure features C—H...O hydrogen bonds and π–π interactions, with a centroid–centroid distance of 3.5728 (16) Å.
Acta Crystallographica Section E Structure Reports Online, 2012