Amino acid N-malonyltransferases from mung beans. Action on 1-aminocyclopropane-1-carboxylic acid and D-phenylalanine.
1-Aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase from etiolated mung bean hypocotyls was examined for its relationship to D-phenylalanine N-malonyltransferase and other enzymes which transfer malonyl groups from malonyl-CoA to D-amino acids. Throughout a 3600-fold purification the ratio of D-phenylalanine N-malonyltransferase activity to ACC N-malonyltransferase activity was unchanged. Antibodies raised against purified ACC N-malonyltransferase 55-kDa protein were also able to precipitate all D-phenylalanine-directed activity from partially purified mung bean extracts. The irreversible inhibitors phenylglyoxal and tetranitromethane reduced malonyltransferase activity towards D-phenylalanine to the same extent as that for ACC. In addition, several other D-amino acids, particularly D-tryptophan and D-tyrosine, were able to inhibit action towards both ACC and D-phenylalanine. These lines of evidence suggest that a single enzyme is capable of promoting malonylation of both ACC and D-phenylalanine. Km values for D-phenylalanine and malonyl-CoA were found to be 48 and 43 microM, respectively; these values are 10-fold lower than the corresponding values when ACC was substrate. Coenzyme A was a noncompetitive (mixed type) product inhibitor towards malonyl-CoA at both unsaturated and saturated ACC concentrations. The enzyme was also inhibited uncompetitively at high concentrations of malonyl-CoA. We propose that the enzyme follows an Ordered Bi-Bi reaction pathway, with the amino acid substrate being bound initially.
Guo
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Department of Horticulture, Pennsylvania State University, University Park 16802.
Phillips
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Arteca
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D000217:Acyltransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000596:Amino Acids / Q000494:pharmacology*; D000598:Amino Acids, Cyclic; D015153:Blotting, Western; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000201:enzymology*; D005998:Glycine / Q000494:pharmacology; D007700:Kinetics; D008970:Molecular Weight; D010649:Phenylalanine / Q000494:pharmacology*; D010658:Phenylglyoxal / Q000494:pharmacology; D010946:Plants, Medicinal; D013237:Stereoisomerism; D013774:Tetranitromethane / Q000494:pharmacology
D000596:Amino Acids; D000598:Amino Acids, Cyclic; C023863:1-aminocyclopropane-1-carboxylic acid; D010649:Phenylalanine; D000217:Acyltransferases; C043949:D-amino acid malonyltransferase; D013774:Tetranitromethane; D010658:Phenylglyoxal; D005998:Glycine