Enzyme systems in the mycobacteria: 14. Fatty acid synthesis in cell-free extracts of Mycobacterium tuberculosis

Abstract

Cell-free extracts of the H37Ra strain of Mycobacterium tuberculosis incorporate acetate and malonate into long-chain fatty acids. ATP, CoA, Mn ++ (or Mg ++), and NADP with isocitrate (or NADPH 2) are required for this incorporation. KHCO 3 is required for acetate incorporation. Acetyl CoA and malonyl CoA are also incorporated into fatty acids. The incorporation of acetate and acetyl CoA into fatty acids is inhibited by avidin; this inhibition is prevented by biotin. The enzyme system is not sedimented by centrifugation at 100,000 × g. The radioactivity (from acetate-1-C 14, etc.) is incorporated into the normal, saturated fatty acids of even carbon number from 16 to 32. Hexacosanoic acid (C-26) is the major product of the system. Malonate (or malonyl CoA) is implicated in this biosynthesis.