Biosynthesis of monacolins: Conversion of monacolin L to monacolin J by a monooxygenase of monascus ruber

Abstract

The microbial metabolites monaeolins J and L are specific inhibitors of 3-hydroxy-3-methylglutaryl Co A reductase, the rate-limiting enzyme in cholesterol synthesis. The producing strain Monascus ruber M 4681 was found to convert exogenously added monacolin L to J. In this hydroxylation reaction 18O2 was incorporated into monacolin L, giving [18O]monacolin J. The cell-free extracts of M. ruber quantitatively hydroxylated monacolin L to J, and molecular oxygen was required for the hydroxylation. The enzyme was located in the microsomal fraction and specific for NADPH. The enzyme activity was inhibited by metyrapone, carbon monoxide, sulfhydryl reagents and cytochrome c. The results indicate that monacolin L is the precursor of monacolin J, and that a monooxygenase is involved in this reaction. © 1989, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.