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排序方式: 共有492条查询结果,搜索用时 15 毫秒
1.
Tapas K. Nandi Hridoy R. Bairagya Bishnu P. Mukhopadhyay K. Sekar Dipankar Sukul Asim K. Bera 《Journal of biosciences》2009,34(1):27-34
The role of invariant water molecules in the activity of plant cysteine protease is ubiquitous in nature. On analysing the
11 different Protein DataBank (PDB) structures of plant thiol proteases, the two invariant water molecules W1 and W2 (W220
and W222 in the template 1PPN structure) were observed to form H-bonds with the Ob atom of Asn 175. Extensive energy minimization and molecular dynamics simulation studies up to 2 ns on all the PDB and solvated
structures clearly revealed the involvement of the H-bonding association of the two water molecules in fixing the orientation
of the asparagine residue of the catalytic triad. From this study, it is suggested that H-bonding of the water molecule at
the W1 invariant site better stabilizes the Asn residue at the active site of the catalytic triad. 相似文献
2.
Dipak K. Das Richard M. Engelman Xuekun Liu Swapna Maity John A. Rousou Joseph Flack Jitendra Laksmipati Randall M. Jones M. Renuka Prasad David W. Deaton 《Molecular and cellular biochemistry》1992,111(1-2):77-86
Reperfusion injury occurs during open-heart surgery after prolonged cardioplegic arrest. Cardiopulmonary bypass also is known to cause hemolysis. Since reperfusion of ischemic myocardium is associated with the generation of oxygen free radicals, and since free radicals can attack a protein molecule, it seems reasonable to assume that hemolysis might be the consequence of free radical attack on hemoglobin protein. The results of this study demonstrated that reperfusion following ischemic arrest caused an increase in free hemoglobin and free heme concentrations, simultaneously releasing free iron and generating hydroxyl radicals. In vitro studies using pure hemoglobin indicated that superoxide anion generated by the action of xanthine oxidase on xanthine could release iron from the heme ring and cause deoxygenation of oxyhemoglobin into ferrihemoglobin. This study further demonstrated that before the release of iron from the heme nucleus, oxyhemoglobin underwent deoxygenation to ferrihemoglobin. The released iron can catalyze the Fenton reaction, leading to the formation of cytotoxic hydroxyl radical (OH·). In fact, the formation of OH. in conjunction with hemolysis occurs during cardiac surgery, and when viewed in the light of the in vitro results, it seems likely that oxygen-derived free radicals may cause hemolysis during cardiopulmonary bypass and simultaneously release iron from the heme ring, which can catalyze the formation of OH·. 相似文献
3.
We develop a new method for variable selection in a nonlinear additive function-on-scalar regression (FOSR) model. Existing methods for variable selection in FOSR have focused on the linear effects of scalar predictors, which can be a restrictive assumption in the presence of multiple continuously measured covariates. We propose a computationally efficient approach for variable selection in existing linear FOSR using functional principal component scores of the functional response and extend this framework to a nonlinear additive function-on-scalar model. The proposed method provides a unified and flexible framework for variable selection in FOSR, allowing nonlinear effects of the covariates. Numerical analysis using simulation study illustrates the advantages of the proposed method over existing variable selection methods in FOSR even when the underlying covariate effects are all linear. The proposed procedure is demonstrated on accelerometer data from the 2003–2004 cohorts of the National Health and Nutrition Examination Survey (NHANES) in understanding the association between diurnal patterns of physical activity and demographic, lifestyle, and health characteristics of the participants. 相似文献
4.
5.
A recent study from our laboratory indicated additional tissue injury during rewarming of a cooled rabbit leg. Oxygen-derived free radicals were believed to play a role in such "rewarming injury." Since free radicals may attack membrane phospholipids, we analyzed the phospholipid composition in the leg tissue during cooling and rewarming. Our results indicated significant breakdown of membrane phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine, with a corresponding accumulation of lysophosphatidylcholine and nonesterified fatty acids. Quinacrine, a phospholipase inhibitor, was able to preserve membrane phospholipids during rewarming of the cooled leg. Rewarming of cooled tissue was also accompanied by additional tissue injury, as evidenced by the increased release of lactic acid dehydrogenase and creatine kinase, as well as enhanced lipid peroxidation, as evidenced by increased malonaldehyde formation. Quinacrine reduced the release of these intracellular enzymes and decreased lipid peroxidation, suggesting its efficacy as a therapeutic agent against hypothermic injury. 相似文献
6.
Effect of high doses of cobra venom (150 micrograms/120 +/- 20 g body weight) and viper venom (300 micrograms/120 +/- 20 g body weight) on total lipid, triglyceride, phospholipid, cholesterol, high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) of brain of albino rats was studied. Total lipid (TL) triglyceride (TG) and phospholipid (PL) are decreased in both viper and cobra venom treated groups while cholesterol (C), and LDL-C are increased in both the groups in relation to controlled ones. HDL-C content was almost unaltered. Decrease in triglyceride and phospholipid may be due to effect of lipases and phospholipases whereas increased cholesterol and LDL-C may be attributed to lysis of cell membrane. 相似文献
7.
Purification and characterization of myo-inositol hexaphosphate-adenosine diphosphate phosphotransferase from Phaseolus aureus 总被引:2,自引:0,他引:2
S Biswas I B Maity S Chakrabarti B B Biswas 《Archives of biochemistry and biophysics》1978,185(2):557-566
myo-Inositol hexaphosphate adenosine diphosphate phosphotransferase transfers phosphate from myo-inositol hexaphosphate to adenosine diphosphate to synthesize adenosine triphosphate. This enzyme has been isolated and purified from ungerminated mungbean seeds and found to be different from guanosine diphosphate phosphotransferase. A purification of about 200-fold with 15% recovery has been obtained. The optimal pH of the reaction is 7.0 and is dependent on the presence of a divalent cation, i.e., Mg2+ and Mn2+. The Km value for myo-inositol hexaphosphate has been found to be 0.41 × 10?4m and V is 90.0 nmol of Pi transferred per milligram of protein per 20 min. Km for ADP is 0.88 × 10-4m and V is 83.3 nmol of phosphorus transferred to ADP per milligram of protein per 20 min. The ADP phosphotransferase reaction is reversible to the extent of about 50% of the forward reaction. dADP is partly effective as an acceptor but other ribonucleoside mono- and diphosphates cannot substitute for ADP. The products ATP and myo-inositol pentaphosphate have been confirmed by several criteria. It has also been shown that this enzyme transfers phosphate only from a specific phosphoryl group (C-2 position) of myo-inositol hexaphosphate for the synthesis of ATP and 1,3,4,5,6-myo-inositol pentaphosphate or pentakis (dihydrogen phosphate). 相似文献
8.
Dipankar Sen 《Phytochemistry》1975,14(7):1505-1506
For measurement of cytochrome c oxidase activity in intact plant mitochondria the optimum concentration of K-Pi buffer and pH in the reaction was found to be 75 mM and 7.4 respectively. The suitable concentration of K-Pi buffer for suspending and storing mitochondria, however, was found to be 20 mM or lower. These requirements applied equally well for mitochondria from wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), maize (Zea mays L.), and snap bean (Phaseolus vulgaris L.). 相似文献
9.
Volpi Denise Alves Fabiana Villa da Silva Arguelho Alan do Vale Marcos Martinez Deniz Matheus Zopollatto Maity 《International journal of biometeorology》2021,65(10):1695-1705
International Journal of Biometeorology - The aim of this study was to estimate, using data mining, which microclimate and behavioral variables affect the behavior of animals to seek shaded or... 相似文献
10.
Terence J. Walton Dipankar Ghosh Russell P. Newton A. Gareth Brenton Frank M. Harris 《Nucleosides, nucleotides & nucleic acids》2013,32(7):967-983
Abstract The use of positive ion fast atom bombardment mass-analysed ion kinetic energy (FAB/MIKE) spectroscopy to differentiate the 2′, 3′-and 5′-monophosphate isomers of adenosine, guanosine and cytidine is described. 相似文献