Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 4-methylene-L-glutamine amidohydrolase has been partially purified from leaf extracts of 2-week germinated peanuts (Arachis hypogaea). Purification steps include DEAE-Sephacel and gel filtration chromatography as well as chromatofocusing; amidohydrolase purified 300- to 400-fold is obtained. The enzyme has an approximate molecular weight of 45,000 as determined by gel filtration chromatography and polyacrylamide gel electrophoresis, a broad activity optimum between pH 8.0 and 9.0, and is highly specific toward 4-methylene-L-glutamine. Of a number of amides tested as substrate, only L-glutamine serves 20% as effectively as the methylene-substituted analog. Multiple bands of activity, seen when enzyme samples are electrophoresed on polyacrylamide gels, are not completely resolved but appear to be very similar in molecular weight, pK values, and subcellular localization. Activity is not affected either by added thiols, metal ions, sulfhydryl-reacting reagents, or metal-ion chelators; it is inhibited by borate ions but stimulated by sodium dodecyl sulfate. This amidohydrolase activity is absent in imbibed seeds, but on germination increases rapidly in the cotyledons and leaves for 3 weeks followed by a gradual decline as the plant matures. Activity is almost completely (95%) localized in the leaves and cotyledons. Differential centrifugation studies indicate that the enzyme is found solely in the soluble fraction of peanut leaves.
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PMID:Purification and properties of a 4-methylene-L-glutamine amidohydrolase from peanut leaves. 686 6

4-Methyleneglutamine amidohydrolase has been extracted and purified over 1000-fold from 14-day-old peanut (Arachis hypogaea) leaves by modification of methods described previously. The purified enzyme shows two bands of activity and three to four bands of protein after electrophoresis on nondenaturing gels. Each of the active bands is readily eluted from gel slices and migrates to its original position on subsequent electrophoresis. Although they are electrophoretically distinct, the two forms of the enzyme are immunologically identical by Ouchterlony double-diffusion techniques and have similar catalytic properties. Activity toward glutamine that has a threefold lower V(max) and a four-fold higher K(m) value copurifies with MeGln aminohydrolase activity. 4-Methyleneglutamine and 4-methyleneglutamic acid inhibit the hydrolysis of glutamine while glutamine inhibits 4-methyleneglutamine hydrolysis, further indicating the identity of the activity toward both substrates. Amidohydrolase activity is stimulated up to threefold by preincubation with either ionic or non-ionic detergents (0.1%) and also by added proteins (0.5% bovine serum albumin or whole rabbit serum); it is inhibited 50% by 1 millimolar borate or the glutamine analog, albizziin (10 millimolar). Rabbit antiserum to the purified peanut enzyme cross-reacts with one or more proteins in extracts of some plants but not others; in no instance, however, was 4-methyleneglutamine amidohydrolase activity detected in other species. Overall, the results support the hypothesis that 4-methyleneglutamine supplies N, via its hydrolysis by the amidohydrolase, to the growing shoots of peanut plants, whereas glutamine hydrolysis is prevented by the prepon-derance of the preferred substrate. Some results also suggest that this amidohydrolase activity may be regulated by metabolites and/or by association with other cellular components.
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PMID:4-methyleneglutamine amidohydrolase from peanut leaves : preparation, catalytic properties, and immunological responses of a highly purified form of the enzyme. 1666 52