In bilaterally ovariectomized specimens of Clarias batrachus effects of 17 beta-estradiol and tes... more In bilaterally ovariectomized specimens of Clarias batrachus effects of 17 beta-estradiol and testosterone propionate (TP) treatment on prolactin content of the pituitary gland and blood serum were investigated. Once daily injection of- beta estradiol (100 microgram/fish augmented the release of prolactin without altering its synthesis. Higher dose of this steroid (150 microgram/fish) significantly accelerated the synthesis and release of prolactin. Similar treatment with TP was uneffective in ovariectomized C. batrachus. It was evident from the data that 17 beta-estradiol is one of the effective regulators of prolactin secretion in female C. batrachus.
The two glycosylated N- and C-terminal lobes of buffalo lactoferrin have been produced by limited... more The two glycosylated N- and C-terminal lobes of buffalo lactoferrin have been produced by limited proteolysis using proteinase K. Lactoferrin is a single chain glycoprotein of molecular mass 80 kDa with two iron-binding sites and two structural lobes connected by a short peptide. Purified samples of lactoferrin, isolated from buffalo colostrum, were subjected to hydrolysis using trypsin, chymotrypsin, pepsin, subtilisin and proteinase K. The first three proteinases produced two major fragments of approximately 35 and 23 kDa together with small molecular mass peptides. Trypsin and chymotrypsin partly digested lactoferrin, while pepsin converted all the intact lactoferrin into fragments. Subtilisin hydrolysis produced fragments of 40 and 26 kDa together with low molecular mass peptides. However, SDS-PAGE of the proteinase K hydrolysis product gave a clear band at 40 kDa together with a band indicating a substantial quantity of low molecular mass peptides (< 14.4 kDa). Upon ion-exchange chromatography this product gave two major fractions, which were further purified by gel filtration and identified as the C and N lobes from their N-terminal sequences. Thus, the 40 kDa band in SDS-PAGE of the proteinase K hydrolysis product contained two fragments of equal molecular mass. On further hydrolysis with proteinase K, the N lobe was completely hydrolysed into low molecular mass peptides, while only a small fraction of the C lobe was converted into small products. This suggested that an inhibitory fragment was present in the C lobe that was released on hydrolysis to small fragments and prevented complete digestion of the C lobe by high-affinity binding to the active site of proteinase K. This fragment was isolated from the lactoferrin-proteinase K complex and its sequence determined to be Val-Ala-Gln-Gly-Gly-Ala-Ala-Gly-Leu-Ala. Circular dichroism studies indicated a high alpha-helical content in the native lactoferrin while comparatively lower helical structures were present in the N and C lobes. In addition, the iron saturations of the N and C lobes appeared to be lower than that of the native protein.
Zinc A2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important... more Zinc A2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important functions in the human body, including fertilization and lipid mobilization. After the discovery of this molecule, during the last 5 decades, various studies have been documented on its structure and functions, but still, it is considered as a protein with an unknown function. Its expression is regulated by glucocorticoids. Due to its high sequence homology with lipid-mobilizing factor and high expression in cancer cachexia, it is considered as a novel adipokine. On the other hand, structural organization and fold is similar to MHC class I antigen-presenting molecule; hence, ZAG may have a role in the expression of the immune response. The function of ZAG under physiologic and cancerous conditions remains mysterious but is considered as a tumor biomarker for various carcinomas. There are several unrelated functions that are attributed to ZAG, such as RNase activity, regulation of melanin production, hindering tumor proliferation, and transport of nephritic by-products. This article deals with the discussion of the major aspects of ZAG from its gene structure to function and metabolism. (Mol Cancer Res 2008;6(6):892 -906)
Selection of quality seedlings in nursery is important for raising fast-growing trees for product... more Selection of quality seedlings in nursery is important for raising fast-growing trees for production of fuelwood and other products. In order to identify the morphophysiological variables that can be used in nursery for selection purpose, a study on growth, drymatter production, and rate of photosynthesis was undertaken with seedlings of four tree species, viz, Acacia nilotica, Albizzia lebbeck, Dalbergia sissoo and Eucalyptus camaldulensis. The species varied significantly in growth, drymatter production and photosynthetic rate in nursery. E. camaldulensis was the fastest in growth and A. nilotica had maximum number of leaves. Total drymatter production was maximum in D. sissoo followed by A. lebbeck. The rate of photosynthesis was maximum in D. sissoo followed by A. nilotica and lowest in A. lebbeck. Among the various seedling attributes, height, number of leaves per plant, rootweight and photosynthetic rate exhibited significant correlations with seedling drymatter. Seedling diameter showed weak positive correlations with drymatter of both seedlings as well as two-year old field trees. However, number of leaves per plant, rootweight, shootweight and leafweight showed significant correlations with two-year field tree drymatter, the strongest correlation (r = 0.96, P = 0.001) was found between number of leaves per plant and field tree drymatter. Although plant height and leaf photosynthetic rate showed a positive correlation with two-year field growth, the relationship was statistically non-significant. The study reveals that maximum value for leaf number and dryweight of seedling components such as root, shoot and leaf can be used as criteria for selecting nursery stocks for field planting in semiarid conditions.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, Jun 1, 2013
Acinetobacter baumannii is a virulent pathogenic bacterium that is resistant to most currently av... more Acinetobacter baumannii is a virulent pathogenic bacterium that is resistant to most currently available antibiotics. Therefore, the design of drugs for the treatment of infections caused by A. baumannii is urgently required. Dihydrodipicolinate reductase (DHDPR) is an important enzyme which is involved in the biosynthetic pathway that leads to the production of L-lysine in bacteria. In order to design potent inhibitors against this enzyme, its detailed three-dimensional structure is required. DHDPR from A. baumannii (AbDHDPR) has been cloned, expressed, purified and crystallized. Here, the preliminary X-ray crystallographic data of AbDHDPR are reported. The crystals were grown using the hanging-drop vapour-diffusion method with PEG 3350 as the precipitating agent The crystals belonged to the orthorhombic space group P222, with unit-cell parameters a = 80.0, b = 100.8, c = 147.6 Å, and contained four molecules in the asymmetric unit. The complete structure determination of AbDHDPR is in progress.
Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also... more Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also includes thyroid peroxidase (TPO). These two enzymes have a sequence homology of 76%. The structure of LPO is known but not that of TPO. In order to determine the mode of binding of antithyroid drugs to thyroid peroxidase, we have determined the crystal structure of LPO complexed with an antithyroid drug, methimazole (MMZ) at 1.97 Å resolution. LPO was isolated from caprine colostrum, purified to homogeneity and crystallized with 20% poly(ethylene glycol)-3350. Crystals of LPO were soaked in a reservoir solution containing MMZ. The structure determination showed the presence of two crystallographically independent molecules in the asymmetric unit. Both molecules contained one molecule of MMZ, but with different orientations. MMZ was held tightly between the heme moiety on one side and the hydrophobic parts of the side chains of Arg255, Glu258, and Leu262 on the opposite side. The back o...
A rapid fluorofunctionalization of alkenes and diene using selectfluor™ has been uncovered. The o... more A rapid fluorofunctionalization of alkenes and diene using selectfluor™ has been uncovered. The olefins such as 1-phenyl ethene; 1,1-diphenylethene; (E)-1,2-diphenylethene; (E)-1,2-dinaphthylethene; 1,1,2-triphenylethene; 1,1,2,2-tetraphenylethene and 1,1,4-triphenyl-1,3-butadiene react with selectfluor™ (F-TEDA-BF4) in water and methanol to give α-fluorohydrins and α-fluoromethoxy compounds respectively under microwave radiations. The electrophilic addition of ‘FOH’ and ‘FOMe’ on the double bond occurs regioselectively with excellent yield.A rapid fluorofunctionalization of phenyl substituted alkenes using selectfluor™ (F-TEDA-BF4) in water and methanol occurs to give α-fluorohydrins and α-fluoromethoxy compounds respectively under microwave radiations. The electrophilic addition of ‘FOH’ and ‘FOMe’ on the double bond takes place regioselectively with excellent yield.► A rapid fluorofunctionalization of alkenes occurs using selectfluor™ and microwaves. ► Phenyl group plays a crucial role during the fluorofunctionalization of alkenes. ► Addition of ‘FOH’ and ‘FOMe’ takes place regioselectively on alkenes.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, Apr 1, 2007
A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized... more A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitating agent. The crystals belong to the tetragonal space group P43212, with unit-cell parameters a = b = 75.8, c = 150.9 Å. The crystals contain two molecules in the asymmetric unit with a VM value of 2.5 Å3 Da−1. Diffraction was observed to 2.65 Å resolution and a complete data set was collected to 2.9 Å resolution.
... PU.30. Authors Sandeep Kumar; Singh, TB Journal Asian Journal of Soil Science 2008 Vol. 3 No.... more ... PU.30. Authors Sandeep Kumar; Singh, TB Journal Asian Journal of Soil Science 2008 Vol. 3 No. 2 pp. ... PU-30 was studied in a sandy clay loam soil of eastern Uttar Pradesh, India, during the kharif seasons of 2005 and 2006. ...
Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the o... more Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the oxidation of halides and pseudohalides in presence of hydrogen peroxide. LPO has been co-crystallized with inorganic substrates, SCN(-), I(-), Br(-) and Cl(-). The structure determination of the complex of LPO with above four substrates showed that all of them occupied distinct positions in the substrate binding site on the distal heme side. The bound substrate ions were separated from each other by one or more water molecules. The heme iron is coordinated to His-351 N(ϵ2) on the proximal side while it is coordinated to conserved water molecule W-1 on the distal heme side. W-1 is hydrogen bonded to Br(-) ion which is followed by Cl(-) ion with a hydrogen bonded water molecule W-5' between them. Next to Cl(-) ion is a hydrogen bonded water molecule W-7' which in turn is hydrogen bonded to W-8' and N atom of SCN(-). W-80 is hydrogen bonded to W-9' which is hydrogen bonded to I(-). SCN(-) ion also interacts directly with Asn-230 and through water molecules with Ser-235 and Phe-254. Therefore, according to the locations of four substrate anions, the order of preference for binding to lactoperoxidase is observed as Br(-)…
International Journal of Biochemistry and Molecular Biology, 2013
Several plant-derived allergens have been identified which result in the formation of immunoglobu... more Several plant-derived allergens have been identified which result in the formation of immunoglobulin E antibodies. Primarily, these allergens belong to the protein families including seed storage proteins, structural proteins and pathogenesis-related proteins. Several allergens are also reported from flower bulbs which cause contact dermatitis. Such symptoms are highly common with the bulb growers handling different species of Narcissus. Narcissus toxicity is also reported if the bulbs are consumed accidentally. The present study aimed to characterize the protein from the bulbs of Narcissus tazetta responsible for its allergenic response. A 13 kDa novel allergenic protein, Narcin was isolated from the bulbs of Narcissus tazetta. The protein was extracted using ammonium sulfate fractionation. The protein was further purified by anion exchange chromatography followed by gel filtration chromatography. The N-terminal sequence of the first 15 amino-acid residues was determined using Edman degradation. The allergenicity of the protein was measured by cytokine production using flow cytometry in peripheral blood mononuclear cells. Further estimation of total IgE was performed by ELISA method. This novel protein was found to induce pro-inflammatory cytokines and thus induce allergy by elevating total IgE level. The novel protein, Narcin isolated from Narcissus tazetta was found to exhibit allergenic properties.
The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythr... more The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC). The orderly degradation of PBS was observed under starvation conditions. A 14 kDa truncated fragment of a-subunit of PE (F-aPE) was identified from the degraded product. F-aPE was purified to homogeneity, sequenced and crystallized. The merohedrally twinned crystals with a twinning factor of approximately 0.5 were obtained. The crystal structure of F-aPE was determined with molecular replacement method using detwinned data and refined to an R cryst factor of 23.2% (R free = 27.6%). The structure consisted of two crystallographically independent molecules in the asymmetric unit. The two molecules were designated as molecules A and B with a buried area of 200 Å 2 at the interface. The structure of F-aPE consists of seven a-helices A, B, E, F, F 0 , G and H. The first 31 N-terminal residues that fold into parallel a-helices X and Y in other PEs are not present in the amino acid sequence of F-aPE. Both molecules, A and B contain two chromophore ligands, PEB1 and PEB2 in each. These are covalently linked to the polypeptide chain through Cys82 and Cys139, respectively. The superimposition of C a tracings of molecules A and B shows an r.m.s. shift of 1.0 Å A 0 indicating that the structures of two independent molecules are very similar. The degradation of phycobilisome proteins under starvation stress seems to occur to supplement the requirement of amino acids for protein synthesis and to reduce the absorption of light energy.
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.
In bilaterally ovariectomized specimens of Clarias batrachus effects of 17 beta-estradiol and tes... more In bilaterally ovariectomized specimens of Clarias batrachus effects of 17 beta-estradiol and testosterone propionate (TP) treatment on prolactin content of the pituitary gland and blood serum were investigated. Once daily injection of- beta estradiol (100 microgram/fish augmented the release of prolactin without altering its synthesis. Higher dose of this steroid (150 microgram/fish) significantly accelerated the synthesis and release of prolactin. Similar treatment with TP was uneffective in ovariectomized C. batrachus. It was evident from the data that 17 beta-estradiol is one of the effective regulators of prolactin secretion in female C. batrachus.
The two glycosylated N- and C-terminal lobes of buffalo lactoferrin have been produced by limited... more The two glycosylated N- and C-terminal lobes of buffalo lactoferrin have been produced by limited proteolysis using proteinase K. Lactoferrin is a single chain glycoprotein of molecular mass 80 kDa with two iron-binding sites and two structural lobes connected by a short peptide. Purified samples of lactoferrin, isolated from buffalo colostrum, were subjected to hydrolysis using trypsin, chymotrypsin, pepsin, subtilisin and proteinase K. The first three proteinases produced two major fragments of approximately 35 and 23 kDa together with small molecular mass peptides. Trypsin and chymotrypsin partly digested lactoferrin, while pepsin converted all the intact lactoferrin into fragments. Subtilisin hydrolysis produced fragments of 40 and 26 kDa together with low molecular mass peptides. However, SDS-PAGE of the proteinase K hydrolysis product gave a clear band at 40 kDa together with a band indicating a substantial quantity of low molecular mass peptides (< 14.4 kDa). Upon ion-exchange chromatography this product gave two major fractions, which were further purified by gel filtration and identified as the C and N lobes from their N-terminal sequences. Thus, the 40 kDa band in SDS-PAGE of the proteinase K hydrolysis product contained two fragments of equal molecular mass. On further hydrolysis with proteinase K, the N lobe was completely hydrolysed into low molecular mass peptides, while only a small fraction of the C lobe was converted into small products. This suggested that an inhibitory fragment was present in the C lobe that was released on hydrolysis to small fragments and prevented complete digestion of the C lobe by high-affinity binding to the active site of proteinase K. This fragment was isolated from the lactoferrin-proteinase K complex and its sequence determined to be Val-Ala-Gln-Gly-Gly-Ala-Ala-Gly-Leu-Ala. Circular dichroism studies indicated a high alpha-helical content in the native lactoferrin while comparatively lower helical structures were present in the N and C lobes. In addition, the iron saturations of the N and C lobes appeared to be lower than that of the native protein.
Zinc A2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important... more Zinc A2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important functions in the human body, including fertilization and lipid mobilization. After the discovery of this molecule, during the last 5 decades, various studies have been documented on its structure and functions, but still, it is considered as a protein with an unknown function. Its expression is regulated by glucocorticoids. Due to its high sequence homology with lipid-mobilizing factor and high expression in cancer cachexia, it is considered as a novel adipokine. On the other hand, structural organization and fold is similar to MHC class I antigen-presenting molecule; hence, ZAG may have a role in the expression of the immune response. The function of ZAG under physiologic and cancerous conditions remains mysterious but is considered as a tumor biomarker for various carcinomas. There are several unrelated functions that are attributed to ZAG, such as RNase activity, regulation of melanin production, hindering tumor proliferation, and transport of nephritic by-products. This article deals with the discussion of the major aspects of ZAG from its gene structure to function and metabolism. (Mol Cancer Res 2008;6(6):892 -906)
Selection of quality seedlings in nursery is important for raising fast-growing trees for product... more Selection of quality seedlings in nursery is important for raising fast-growing trees for production of fuelwood and other products. In order to identify the morphophysiological variables that can be used in nursery for selection purpose, a study on growth, drymatter production, and rate of photosynthesis was undertaken with seedlings of four tree species, viz, Acacia nilotica, Albizzia lebbeck, Dalbergia sissoo and Eucalyptus camaldulensis. The species varied significantly in growth, drymatter production and photosynthetic rate in nursery. E. camaldulensis was the fastest in growth and A. nilotica had maximum number of leaves. Total drymatter production was maximum in D. sissoo followed by A. lebbeck. The rate of photosynthesis was maximum in D. sissoo followed by A. nilotica and lowest in A. lebbeck. Among the various seedling attributes, height, number of leaves per plant, rootweight and photosynthetic rate exhibited significant correlations with seedling drymatter. Seedling diameter showed weak positive correlations with drymatter of both seedlings as well as two-year old field trees. However, number of leaves per plant, rootweight, shootweight and leafweight showed significant correlations with two-year field tree drymatter, the strongest correlation (r = 0.96, P = 0.001) was found between number of leaves per plant and field tree drymatter. Although plant height and leaf photosynthetic rate showed a positive correlation with two-year field growth, the relationship was statistically non-significant. The study reveals that maximum value for leaf number and dryweight of seedling components such as root, shoot and leaf can be used as criteria for selecting nursery stocks for field planting in semiarid conditions.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, Jun 1, 2013
Acinetobacter baumannii is a virulent pathogenic bacterium that is resistant to most currently av... more Acinetobacter baumannii is a virulent pathogenic bacterium that is resistant to most currently available antibiotics. Therefore, the design of drugs for the treatment of infections caused by A. baumannii is urgently required. Dihydrodipicolinate reductase (DHDPR) is an important enzyme which is involved in the biosynthetic pathway that leads to the production of L-lysine in bacteria. In order to design potent inhibitors against this enzyme, its detailed three-dimensional structure is required. DHDPR from A. baumannii (AbDHDPR) has been cloned, expressed, purified and crystallized. Here, the preliminary X-ray crystallographic data of AbDHDPR are reported. The crystals were grown using the hanging-drop vapour-diffusion method with PEG 3350 as the precipitating agent The crystals belonged to the orthorhombic space group P222, with unit-cell parameters a = 80.0, b = 100.8, c = 147.6 Å, and contained four molecules in the asymmetric unit. The complete structure determination of AbDHDPR is in progress.
Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also... more Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also includes thyroid peroxidase (TPO). These two enzymes have a sequence homology of 76%. The structure of LPO is known but not that of TPO. In order to determine the mode of binding of antithyroid drugs to thyroid peroxidase, we have determined the crystal structure of LPO complexed with an antithyroid drug, methimazole (MMZ) at 1.97 Å resolution. LPO was isolated from caprine colostrum, purified to homogeneity and crystallized with 20% poly(ethylene glycol)-3350. Crystals of LPO were soaked in a reservoir solution containing MMZ. The structure determination showed the presence of two crystallographically independent molecules in the asymmetric unit. Both molecules contained one molecule of MMZ, but with different orientations. MMZ was held tightly between the heme moiety on one side and the hydrophobic parts of the side chains of Arg255, Glu258, and Leu262 on the opposite side. The back o...
A rapid fluorofunctionalization of alkenes and diene using selectfluor™ has been uncovered. The o... more A rapid fluorofunctionalization of alkenes and diene using selectfluor™ has been uncovered. The olefins such as 1-phenyl ethene; 1,1-diphenylethene; (E)-1,2-diphenylethene; (E)-1,2-dinaphthylethene; 1,1,2-triphenylethene; 1,1,2,2-tetraphenylethene and 1,1,4-triphenyl-1,3-butadiene react with selectfluor™ (F-TEDA-BF4) in water and methanol to give α-fluorohydrins and α-fluoromethoxy compounds respectively under microwave radiations. The electrophilic addition of ‘FOH’ and ‘FOMe’ on the double bond occurs regioselectively with excellent yield.A rapid fluorofunctionalization of phenyl substituted alkenes using selectfluor™ (F-TEDA-BF4) in water and methanol occurs to give α-fluorohydrins and α-fluoromethoxy compounds respectively under microwave radiations. The electrophilic addition of ‘FOH’ and ‘FOMe’ on the double bond takes place regioselectively with excellent yield.► A rapid fluorofunctionalization of alkenes occurs using selectfluor™ and microwaves. ► Phenyl group plays a crucial role during the fluorofunctionalization of alkenes. ► Addition of ‘FOH’ and ‘FOMe’ takes place regioselectively on alkenes.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, Apr 1, 2007
A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized... more A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitating agent. The crystals belong to the tetragonal space group P43212, with unit-cell parameters a = b = 75.8, c = 150.9 Å. The crystals contain two molecules in the asymmetric unit with a VM value of 2.5 Å3 Da−1. Diffraction was observed to 2.65 Å resolution and a complete data set was collected to 2.9 Å resolution.
... PU.30. Authors Sandeep Kumar; Singh, TB Journal Asian Journal of Soil Science 2008 Vol. 3 No.... more ... PU.30. Authors Sandeep Kumar; Singh, TB Journal Asian Journal of Soil Science 2008 Vol. 3 No. 2 pp. ... PU-30 was studied in a sandy clay loam soil of eastern Uttar Pradesh, India, during the kharif seasons of 2005 and 2006. ...
Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the o... more Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the oxidation of halides and pseudohalides in presence of hydrogen peroxide. LPO has been co-crystallized with inorganic substrates, SCN(-), I(-), Br(-) and Cl(-). The structure determination of the complex of LPO with above four substrates showed that all of them occupied distinct positions in the substrate binding site on the distal heme side. The bound substrate ions were separated from each other by one or more water molecules. The heme iron is coordinated to His-351 N(ϵ2) on the proximal side while it is coordinated to conserved water molecule W-1 on the distal heme side. W-1 is hydrogen bonded to Br(-) ion which is followed by Cl(-) ion with a hydrogen bonded water molecule W-5' between them. Next to Cl(-) ion is a hydrogen bonded water molecule W-7' which in turn is hydrogen bonded to W-8' and N atom of SCN(-). W-80 is hydrogen bonded to W-9' which is hydrogen bonded to I(-). SCN(-) ion also interacts directly with Asn-230 and through water molecules with Ser-235 and Phe-254. Therefore, according to the locations of four substrate anions, the order of preference for binding to lactoperoxidase is observed as Br(-)…
International Journal of Biochemistry and Molecular Biology, 2013
Several plant-derived allergens have been identified which result in the formation of immunoglobu... more Several plant-derived allergens have been identified which result in the formation of immunoglobulin E antibodies. Primarily, these allergens belong to the protein families including seed storage proteins, structural proteins and pathogenesis-related proteins. Several allergens are also reported from flower bulbs which cause contact dermatitis. Such symptoms are highly common with the bulb growers handling different species of Narcissus. Narcissus toxicity is also reported if the bulbs are consumed accidentally. The present study aimed to characterize the protein from the bulbs of Narcissus tazetta responsible for its allergenic response. A 13 kDa novel allergenic protein, Narcin was isolated from the bulbs of Narcissus tazetta. The protein was extracted using ammonium sulfate fractionation. The protein was further purified by anion exchange chromatography followed by gel filtration chromatography. The N-terminal sequence of the first 15 amino-acid residues was determined using Edman degradation. The allergenicity of the protein was measured by cytokine production using flow cytometry in peripheral blood mononuclear cells. Further estimation of total IgE was performed by ELISA method. This novel protein was found to induce pro-inflammatory cytokines and thus induce allergy by elevating total IgE level. The novel protein, Narcin isolated from Narcissus tazetta was found to exhibit allergenic properties.
The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythr... more The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC). The orderly degradation of PBS was observed under starvation conditions. A 14 kDa truncated fragment of a-subunit of PE (F-aPE) was identified from the degraded product. F-aPE was purified to homogeneity, sequenced and crystallized. The merohedrally twinned crystals with a twinning factor of approximately 0.5 were obtained. The crystal structure of F-aPE was determined with molecular replacement method using detwinned data and refined to an R cryst factor of 23.2% (R free = 27.6%). The structure consisted of two crystallographically independent molecules in the asymmetric unit. The two molecules were designated as molecules A and B with a buried area of 200 Å 2 at the interface. The structure of F-aPE consists of seven a-helices A, B, E, F, F 0 , G and H. The first 31 N-terminal residues that fold into parallel a-helices X and Y in other PEs are not present in the amino acid sequence of F-aPE. Both molecules, A and B contain two chromophore ligands, PEB1 and PEB2 in each. These are covalently linked to the polypeptide chain through Cys82 and Cys139, respectively. The superimposition of C a tracings of molecules A and B shows an r.m.s. shift of 1.0 Å A 0 indicating that the structures of two independent molecules are very similar. The degradation of phycobilisome proteins under starvation stress seems to occur to supplement the requirement of amino acids for protein synthesis and to reduce the absorption of light energy.
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.
Uploads
Papers by TEJ SINGH