http://nopr.niscair.res.in/handle/123456789/3230 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3419 Title: Non-enzymatic glycation of proteins: A cause for complications in diabetes <br/> <br/>Authors: Nawale, R B; Mourya, V K; Bhise, S B <br/> <br/>Abstract: Diabetes mellitus is one of the most common non-communicable diseases, and is the fifth leading cause of death in most of the developed countries. It can affect nearly every organ and system in the body and may result in blindness, end stage renal disease, lower extremity amputation and increase risk of stroke, ischaemic heart diseases and peripheral vascular disease. Hyperglycemia in diabetes causes non-enzymatic glycation of free amino groups of proteins (of lysine residues) and leads to their structural and functional changes, resulting in complications of the diabetes. Glycation of proteins starts with formation of Shiff’s base, followed by intermolecular rearrangement and conversion into Amadori products. When large amounts of Amadori products are formed, they undergo cross linkage to form a heterogeneous group of protein-bound moieties, termed as advanced glycated end products (AGEs). Rate of these reactions are quite slow and only proteins with large amounts of lysine residues undergo glycation with significant amounts of AGEs. The formation of AGEs is a irreversible process, causing structural and functional changes in protein leading to various complications in diabetes like nephropathy, retinopathy, neuropathy and angiopathy. The present review discusses about role of glycation in various complications of diabetes. <br/> <br/>Page(s): 337-344 http://nopr.niscair.res.in/handle/123456789/3418 Title: Overexpression of a recombinant -glutamyltranspeptidase from <br/> <br/>Authors: Yao, Ya-Feng; Weng, Yih-Ming; Hu, Hui-Yu; Lin, Long-Liu <br/> <br/>Abstract: A truncated Escherichia coli Novablue -glutamyltranspeptidase (EcGGT) gene, lacking the first 48-bp coding sequence for part of the signal sequence, was amplified by polymerase chain reaction (PCR) and cloned into expression vector pQE-30 to generate pQE-EcGGT. The maximum production of His6-tagged enzyme by E. coli M15 (pQE-EcGGT) was achieved with 0.1 mM IPTG induction for 12 h at 20°C. The overexpressed enzyme was purified to homogeneity by nickel-chelate chromatography to a specific transpeptidase activity of 4.25 U/mg protein and a final yield of 83%. The molecular masses of the subunits of the purified enzyme were determined to be 41 and 21 kDa respectively by SDS-PAGE, indicating the precursor EcGGT still undergoes the post-translational processing even in the truncation of signal sequence. His6-tagged EcGGT migrated relative to the molecular mass of approximately 120 kDa and its heterodimeric structure was confirmed by a native-PAGE gel. <br/> <br/>Page(s): 345-350 http://nopr.niscair.res.in/handle/123456789/3417 Title: Mechanism of inhibition of Ca2+-transport activity of sarcoplasmic reticulum <br/> <br/>Authors: Pang, Yuhong; Li, Xiaozhu; Qin, Sanbo; Zhang, Hongjie; Chen, Jianwen <br/> <br/>Abstract: The mechanism of inhibition of Ca2+-transport activity of rabbit sarcoplasmic reticulum Ca2+-ATPase (SERCA) by anisodamine (a drug isolated from a medicinal herb Hyoscyamus niger L) was investigated by using ANS (1-anilino-8-naphthalenesulfonate) fluorescence probe, intrinsic fluorescence quenching and Ca2+-transport activity assays. The number of ANS binding sites for apo Ca2+-ATPase was determined as 8, using a multiple-identical binding site model. Both anisodamine and Ca2+ at millimolar level enhanced the ANS binding fluorescence intensities. Only anisodamine increased the number of ANS molecules bound by SERCA from 8 to 14. The dissociation constants of ANS to the enzyme without any ligand, with 30 mM anisodamine and with 15 mM Ca2+ were found to be 53.0 μM, 85.0 μM and 50.1 μM, respectively. Both anisodamine and Ca2+ enhanced the ANS binding fluorescenc with apparent dissociation constants of 7.6 mM and 2.3 mM, respectively, at a constant concentration of the enzyme. Binding of anisodamine significantly decreased the binding capacity of Ca2+ with the dissociation constant of 9.5 mM, but binding of Ca2+ had no obvious effect on binding of anisodamine. Intrinsic fluorescence quenching and Ca2+-transport activity assays gave the dissociation constants of anisodamine to SERCA as 9.7 and 5.4 mM, respectively, which were consistent with those obtained from ANS-binding fluorescence changes during titration of SERCA with anisodamine and anisodamine + 15 mM Ca2+, respectively. The results suggest that anisodamine regulates Ca2+-transport activity of the enzyme, by stabilizing the trans-membrane domain in an expanded, inactive conformation, at least at its annular ring region. <br/> <br/>Page(s): 351-359 http://nopr.niscair.res.in/handle/123456789/3416 Title: A new fragmentation rearrangement of the N-terminal protected <br/> <br/>Authors: Zhu, Zhen-Tai; Li, Yan-Mei; Guo, Yan-Ting; Sun, Ming; Zhao, Yu-Fen <br/> <br/>Abstract: A novel fragmentation rearrangement reaction with a carboxyl oxygen negative charge migration was observed in the N-terminal protected amino acids including Fmoc-protected phosphoserine, phosphothroenine, and phosphotyrosine and their analogues using the electrospray ionization tandem mass spectrometry (ESI-MS/MS). The possible mechanism of a five-membered ring transition state was proposed and supported by the further experiments. It was found that the tendency of the rearrangement was determined by the blocking status of its C-terminal and the reaction was proved to be independent of the N-terminal and side-chain protecting groups of the amino acids. <br/> <br/>Page(s): 372-376