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1.
Scavenging of superoxide radical by ascorbic acid 总被引:1,自引:0,他引:1
Using acetaldehyde and xanthine oxidase as the source of suPeroxide radical, the second order rate constant for the reaction
between ascorbic acid and superoxide radical was estimated to be 8.2 X 107 M-1 s-1. In rats, the average tissue concentration of ascorbic acid was of the order of 10-3 M and that of superoxide dismutase was of the order of 10-6 M. So, taking together both the rate constants and the tissue concentrations, the efficacy of ascorbic acid for scavenging
superoxide radical in animal tissues appears to be better than that of suPeroxide dismutase. The significance of ascorbic
acid as a scavenger of superoxide radical has been discussed from the point of view of the evolution of ascorbic acid synthesizing
capacity of terrestrial vertebrates. 相似文献
2.
The large family of signal transducing proteins known as G proteins are heterotrimers that dissociate into an independent α-subunit and βγ-subunit complex after ligand binding or other stimulation. For Gα, at least 30 distinct sequences representing 10 different classes have been identified. On the other hand, cDNAs for only three Gβ-subunit genes have been isolated so far. All three of the Gβ genes have been chromosomally mapped in the human, but only two in the mouse. Using a human retinal cDNA for the third G protein β-subunit, we have mapped the corresponding gene, termed Gnb-3, to mouse Chromosome 6 with somatic cell hybrids and have positioned it distal to but near the marker Raf-1 by analysis of the progeny of three genetic crosses. 相似文献
3.
Summary In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants. 相似文献
4.
5.
Alterations of Phospholipid Metabolism in Rat Cerebral Cortex Mince Induced by Cationic Amphiphilic Drugs 总被引:3,自引:3,他引:0
Abstract Cationic amphiphilic drugs (CADs) of varied clinical use were screened to determine their capacity to alter the pattern of labeling with 32 Pj of cerebral cortex mince phospholipids. The altered phospholipid labeling patterns were qualitatively similar, the prominent features being reduced incorporation into phosphatidylcholine and increased incorporation into phosphatidic acid. Relative potencies were: (±)-propranolol > chlorpromazine = 4,4'-bis(diethylaminoethoxy) α,β -diethyldiphenylethane > desipramine > di-bucaine > pimozide > oxymetazoline = fenfluramine = haloperidol = chloroquine > amphetamine = no drug added. Propranolol was used to study the action of CADs further. Its effect was time- and dose-dependent, but in contrast with pineal gland, no label appeared in phosphatidyl-CMP (CDP-diacylglycerol), nor did dialysis of the mince to reduce diffusible substrates or exogenous addition of substrates cause appearance of liponucleotide. Thus lack of diffusible precursors is not responsible for CAD effects in vitro. Pulse-chase experiments with 32 P1 and [2-3 H]glycerol suggested that inhibition of phosphatidate phosphohydrolase may be partly responsible for the observed alterations in phospholipid labeling in the presence of CADs. 相似文献
6.
7.
Anuradha Hora 《Preparative biochemistry & biotechnology》2013,43(8):769-784
Hexavalent chromium contamination is a serious problem due to its high toxicity and carcinogenic effects on the biological systems. The enzymatic reduction of toxic Cr(VI) to the less toxic Cr(III) is an efficient technology for detoxification of Cr(VI)-contaminated industrial effluents. In this regard, a chromate reductase enzyme from a novel Ochrobactrum sp. strain Cr-B4, having the ability to detoxify Cr(VI) contaminated sites, has been partially purified and characterized. The molecular mass of this chromate reductase was found to be 31.53 kD, with a specific activity 14.26 U/mg without any addition of electron donors. The temperature and pH optima for chromate reductase activity were 40°C and 8.0, respectively. The activation energy (Ea) for the chromate reductase was found to be 34.7 kJ/mol up to 40°C and the activation energy for its deactivation (Ed) was found to be 79.6 kJ/mol over a temperature range of 50–80°C. The frequency factor for activation of chromate reductase was found to be 566.79 s?1, and for deactivation of chromate reductase it was found to be 265.66 × 103 s?1. The reductase activity of this enzyme was affected by the presence of various heavy metals and complexing agents, some of which (ethylenediamine tetraacetic acid [EDTA], mercaptoethanol, NaN3, Pb2+, Ni2+, Zn2+, and Cd2+) inhibited the enzyme activity, while metals like Cu2+ and Fe3+ significantly enhanced the reductase activity. The enzyme followed Michaelis–Menten kinetics with Km of 104.29 µM and a Vmax of 4.64 µM/min/mg. 相似文献
8.
Renu Goel Krishna R Murthy Srinivas M Srikanth Sneha M Pinto Mitali Bhattacharjee Dhanashree S Kelkar Anil K Madugundu Gourav Dey Sujatha S Mohan Venkatarangaiah Krishna TS Keshava Prasad Shukti Chakravarti HC Harsha Akhilesh Pandey 《Clinical proteomics》2013,10(1):9
Background
The ciliary body is the circumferential muscular tissue located just behind the iris in the anterior chamber of the eye. It plays a pivotal role in the production of aqueous humor, maintenance of the lens zonules and accommodation by changing the shape of the crystalline lens. The ciliary body is the major target of drugs against glaucoma as its inhibition leads to a drop in intraocular pressure. A molecular study of the ciliary body could provide a better understanding about the pathophysiological processes that occur in glaucoma. Thus far, no large-scale proteomic investigation has been reported for the human ciliary body.Results
In this study, we have carried out an in-depth LC-MS/MS-based proteomic analysis of normal human ciliary body and have identified 2,815 proteins. We identified a number of proteins that were previously not described in the ciliary body including importin 5 (IPO5), atlastin-2 (ATL2), B-cell receptor associated protein 29 (BCAP29), basigin (BSG), calpain-1 (CAPN1), copine 6 (CPNE6), fibulin 1 (FBLN1) and galectin 1 (LGALS1). We compared the plasma proteome with the ciliary body proteome and found that the large majority of proteins in the ciliary body were also detectable in the plasma while 896 proteins were unique to the ciliary body. We also classified proteins using pathway enrichment analysis and found most of proteins associated with ubiquitin pathway, EIF2 signaling, glycolysis and gluconeogenesis.Conclusions
More than 95% of the identified proteins have not been previously described in the ciliary body proteome. This is the largest catalogue of proteins reported thus far in the ciliary body that should provide new insights into our understanding of the factors involved in maintaining the secretion of aqueous humor. The identification of these proteins will aid in understanding various eye diseases of the anterior segment such as glaucoma and presbyopia. 相似文献9.
Wareed Ahmed Anuradha Gopal Bhat Majety Naga Leelaram Shruti Menon Valakunja Nagaraja 《Nucleic acids research》2013,41(15):7462-7471
Bacterial DNA topoisomerase I (topoI) carries out relaxation of negatively supercoiled DNA through a series of orchestrated steps, DNA binding, cleavage, strand passage and religation. The N-terminal domain (NTD) of the type IA topoisomerases harbor DNA cleavage and religation activities, but the carboxyl terminal domain (CTD) is highly diverse. Most of these enzymes contain a varied number of Zn2+ finger motifs in the CTD. The Zn2+ finger motifs were found to be essential in Escherichia coli topoI but dispensable in the Thermotoga maritima enzyme. Although, the CTD of mycobacterial topoI lacks Zn2+ fingers, it is indispensable for the DNA relaxation activity of the enzyme. The divergent CTD harbors three stretches of basic amino acids needed for the strand passage step of the reaction as demonstrated by a new assay. We also show that the basic amino acids constitute an independent DNA-binding site apart from the NTD and assist the simultaneous binding of two molecules of DNA to the enzyme, as required during the catalytic step. Although the NTD binds to DNA in a site-specific fashion to carry out DNA cleavage and religation, the basic residues in CTD bind to non-scissile DNA in a sequence-independent manner to promote the crucial strand passage step during DNA relaxation. The loss of Zn2+ fingers from the mycobacterial topoI could be associated with Zn2+ export and homeostasis. 相似文献
10.
Tanuja Rana Anuradha Negi Sunny Dhir Tombisana Thockchom Vanita Chandel Yashika Walia 《Archives Of Phytopathology And Plant Protection》2013,46(6):505-512
Apple is known to be susceptible to various virus and viroid pathogens. Symptomatic apple cultivars and rootstocks were collected and analyzed by ELISA and then through RT-PCR. The study reports the presence of Apple mosaic virus (ApMV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Apple chlorotic leaf spot virus (ACLSV), the major apple viruses and Prunus necrotic ringspot virus (PNRSV), a minor apple virus, at the molecular level in India. Apple scar skin viroid (ASSVd) infection was also confirmed at the molecular level. Sporadic incidences of Tomato ringspot virus and Arabis mosaic virus infections were also detected by ELISA in nursery plants. 相似文献