Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.4 (SOR)
 720 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma membrane isolated by two-phase partition from rat liver showed rates of ascorbate free radical reduction by NADH of 4-5 nmoles of oxidized NADH/min/mg protein. This activity was inhibited 80% by ConA and up to 97% by WGA and LFA lectins. NADH-ascorbate free radical reductase was also inhibited in rat liver plasma membranes preincubated with neuraminidase or trypsin, but no additional inhibition was observed in the presence of LFA after enzyme digestion. It appears that the integrity of glucan moieities of the cell surface glycoconjugates are necessary for the optimal function of this activity that could be considered as part of the transplasma membrane electron transport system.
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PMID:Cell surface glycoconjugates control the activity of the NADH-ascorbate free radical reductase of rat liver plasma membrane. 340 83

Four pairs of M+SOR+ and M-SOR- variants of group-A type-49 streptococci were compared as receptor strains in transduction of a streptomycin-resistance marker. The yield of transductants was 5-9-fold greater with the M-SOR- variants than with the corresponding M+SOR+ variants. Treatment of M+SOR+ variants of type-49 streptococci with trypsin enhanced the rate of transduction by 16-35-fold whereas trypsin treatment of corresponding M-SOR- variants resulted in minimal enhancement (5-fold or less). With trypsin treatment the numbers of transductants were approximately equal in pairs of M+SOR+ and M-SOR- variants. Enhanced transduction (10-26-fold) of streptomycin resistance was obtained by trypsin treatment of another seven M+SOR+ type-49 strains, of diverse phage subtypes and from various geographical locations. A wide range of enhancement (5-46-fold) was found in eight of nine M+ strains of group-A type-6 streptococci. With trypsin treatment, three of 10 transducible group-G strains showed enhanced transduction (10-13-fold) of a plasmid containing a determinant for erythromycin resistance. Transductional enhancement is proteolytic in nature, being enhanced by trypsin, chymotrypsin, papain, pronase and streptococcal proteinase. Although interference with phage adsorption by surface proteins would appear to be the most obvious explanation for these findings, further studies are required to define more clearly the mechanism of trypsin enhancement.
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PMID:Surface proteins in the transduction of groups A and G streptococci. 351 35

In many physiological studies dehydroascorbate (DHA) reductase is regarded as one of the chloroplast enzymes involved in the protection against oxidative stress. Here, evidence is presented that plant cells do not possess a specific DHA reductase. The DHA reductase activities measured in plant extracts are due to side reactions of proteins containing redox-active dicysteine sites. Native gel electrophoresis combined with specific activity staining revealed three different proteins with DHA reductase activity in leaf and chloroplast extracts. These proteins have been identified as thioredoxins and trypsin inhibitors (Kunitz type) by Western blot analysis. The essential regulatory functions of thioredoxins in chloroplast metabolism are strongly inhibited in the presence of as little as 50 microM DHA. Thus, the intracellular DHA concentration should be kept below 50 microM but not all proteins with DHA reductase activity are effective enough for this purpose. A specific DHA reductase is frequently demanded as part of the enzymatic equipment to avoid oxidative stress. We argue that this is not necessary because in chloroplasts DHA does not accumulate to any significant extent due to the high activities of monodehydroascorbate reductase and of reduced ferredoxin.
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PMID:Dehydroascorbate and dehydroascorbate reductase are phantom indicators of oxidative stress in plants. 932 37

Glyoxysomal membranes from germinating castor bean (Ricinus communis L. cv Hale) endosperm contain an NADH dehydrogenase. This enzyme can utilize extraorganellar ascorbate free-radical as a substrate and can oxidize NADH at a rate which can support intraglyoxysomal demand for NAD(+). NADH:ascorbate free-radical reductase was found to be membrane-associated, and the activity remained in the membrane fraction after lysis of glyoxysomes by osmotic shock, followed by pelleting of the membranes. In whole glyoxysomes, NADH:ascorbate free-radical reductase, like NADH:ferricyanide reductase and unlike NADH:cytochrome c reductase, was insensitive to trypsin and was not inactivated by Triton X-100 detergent. These results suggest that ascorbate free-radical is reduced by the same component which reduces ferricyanide in the glyoxysomal membrane redox system. NADH:ascorbate free-radical reductase comigrated with NADH:ferricyanide and cytochrome c reductases when glyoxy-somal membranes were solubilized with detergent and subjected to rate-zonal centrifugation. The results suggest that ascorbate free-radical, when reduced to ascorbate by membrane redox system, could serve as a link between glyoxysomal metabolism and other cellular activities.
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PMID:Ascorbate free-radical reduction by glyoxysomal membranes. 1666 45