Amino acid N-malonyltransferases from mung beans. Action on 1- aminocyclopropane-1-carboxylic acid and D-phenylalanine

L. Guo, A. T. Phillips, R. N. Arteca

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11 Scopus citations

Abstract

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. K(m) values for D-phenylalanine and malonyl-CoA were found to be 48 and 43 μM, 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.

Original languageEnglish (US)
Pages (from-to)25389-25394
Number of pages6
JournalJournal of Biological Chemistry
Volume268
Issue number34
StatePublished - 1993

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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