Hidehiko Tanaka, K. Soda
Aug 25, 1974
Citations
0
Influential Citations
8
Citations
Journal
Journal of Biological Chemistry
Abstract
Abstract Acetyl-CoA: S-(β-aminoethyl)-l-cysteine ω-N-acetyltransferase, an enzyme catalyzing the transfer of acetyl group from acetyl-CoA to the terminal amino group of S-(β-aminoethyl)-l-cysteine, a metabolic antagonist of l-lysine, has been purified about 450-fold from the cell-free extracts of Aerobacter aerogenes. The purified enzyme is homogeneous by the criterion of disc gel electrophoresis and has an approximate molecular weight of 100,000. In addition to S-(β-aminoethyl)-l-cysteine, its d-enantiomer, sulfoxide, sulfone, and higher homolog, and an oxygen analog of lysine, O-(β-aminoethyl)-dl-serine act as acetyl acceptors. l- or d-Lysine and l- or d-ornithine also can accept an acetyl group to a certain extent, but α- or ω-N-acetylated derivatives of both S-(β-aminoethyl)-l-cysteine and l-lysine are not active. Acetyl-CoA is the exclusive acyl donor in the transfer reaction. The following apparent Michaelis constants were determined: S-(β-aminoethyl)-l-cysteine, 2.1 x 10-3 m; S-(β-aminoethyl)-d-cysteine, 1.6 x 10-3 m; O-(β-aminoethyl)-dl-serine, 1.7 x 10-3 m; S-(β-aminoethyl)-l-homocysteine, 7.1 x 10-4; and acetyl-CoA, 4.5 x 10-3 m. The enzyme activity is inhibited competitively in propionyl-CoA, butyryl-CoA, and benzoyl-CoA against acetyl-CoA. S-(β-Aminoethyl)-α-N-acetyl-l-cysteine and S-(β-aminoethyl)-mercaptopropionate are strong competitive inhibitors of S-(β-aminoethyl)-l-cysteine acetylation.