Relationship between 1-aminocyclopropanecarboxylate malonyltransferase and D-amino acid malonyltransferase |
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Authors: | Su Ling-Yuan Liu Yu Fa Yang Shang |
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Institution: | Department of Vegetable Crops, University of California, Davis, CA 95616, U.S.A. |
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Abstract: | An enzyme preparation isolated from mungbean hypocotyls catalyses the malonyl-CoA-dependent N-malonylation of 1-aminocyclopropane-1-carboxylic acid (ACC), D-phenylalanine (Phe), D-methionine and 2-aminoisobutyric acid with Km values of 0.15, 0.8, 3.4 and 5.1 mM, respectively L-enantiomers of Phe and methionine were, however, not malonylated by the enzyme preparation. When ACC was tested on D-Phe malonyltransferase activity, or when D-Phe was tested on ACC malonyltransferase activity, these compounds exhibited competitive inhibition kinetics with Ki values similar to their respective Km values. Such a relationship suggests that malonylations of ACC and D-amino acids are catalysed by the same enzyme. This view was further supported by the observations that the ratio ACC-D-Phe malonyltransferase activities remained constant throughout various fractionation steps and both enzyme activities were inhibited similarly by various sulphydryl reagents and 1-aminocycloalkane-1-carboxylic acids. |
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Keywords: | Leguminosae 1-aminocyclopropane-1-carboxylic acid malonyltransferase ACC 1-aminocyclopropane-1-carboxyclic acid AIB 2-aminoisobutyric acid Ala alanine DTT dithiothreitol Gly glycine MACC 1-(malonylamino)cyclopropane-1-carboxyclic acid MAIB 2(-malonylamino)isobutyric acid Met methionine MetSO methionine sulphoxide Phe phenylalanine |
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