A constitutive peptide antibiotic lactonase opening the lactone linkage of dihydrostaphylomycin S was isolated from
Actinoplanes missouriensis. Approximately 200-fold purification was achieved by ammoniumsulfate precipitation followed by chromatography on calcium phosphate-cellulose, DEAE-cellulose, and Sephadex G-200 columns. The molecular weight, as determined by gel filtration on Sephadex G-200, is 35, 000. The Km value for dihydrostaphylomycin S is 3.73×10
-4M. This enzyme also hydrolyzed the lactone bond in echinomycin, etamycin, staphylomycin S, stendomycin, and vernamycin B
α. The enzyme content of the cells was increased by addition of these peptides and also actinomycin to the growing culture.
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