[A study on indolepyruvic acid methyltransferase in chuangxinmycin-producing strain].

The indolepyruvic acid methyltransferase, perhaps which is active in the biosynthetic pathway of the antibiotic chuangxinmycin, has been detected and partially purified from cell-free extracts of Actinoplanes jinanensis n. sp., This enzyme catalyzes the transfer of a methyl group from S-adenosylmethionine to indolepyruvic acid. The methyltransferase has been purified 60-fold by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The enzyme optimal substrate is indolepyruvic acid. The enzyme has a pH optimum of 7.5. The double reciprocal plots gave Km values of 4.0 X 10(-5) mol/L for S-adenosylmethionine and 1.8 X 10(-7) mol/L for indolepyruvic acid. A molecular weight of 55000 +/- 5000 has been determined by Sephadex G-150 gel filtration.