Biosynthesis of branched-chain fatty acids V. Microbial stereospecific syntheses of d-12-methyltetradecanoic and d-14-methylhexadecanoic acids
Review articleOpen access
1966/08/03 Full-length article DOI: 10.1016/0005-2760(66)90142-1
Journal: Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism
Abstract:
SummaryThe fatty acids produced by Bacillus subtilis (ATCC-7059) include the optically active fatty acids, d(+)12-methyltetradecanoic acid, and d(+)14-methylhexadecanoic acid. Tracer experiments have shown that the terminal portion of the anteiso fatty acids are synthesized from pyruvate and α-ketobutyrate (most likely derived from l-threonine) through α-keto-β-methylvalerate by a mechanism similar to that of the synthesis of l-isoleucine de novo. Furthermore, l(+)α-keto-β-methylvalerate, the α-keto acid of l-isoleucine, was incorporated into the terminal-C5 portions with no change in stereoconfiguration at the β-carbon, presumably through the formation of d-α-methylbutyryl CoA. d(−)α-Keto-β-methylvalerate, the α-keto acid of l-alloisoleucine, was incorporated after conversion to its l isomer. d(+)α-Methylbutyrate, stereochemically related to l-isoleucine, was utilized but not its l isomer. In all cases, the d isomer of the anteiso fatty acids was the only product regardless of whether the d or the l isomer of precursor was administered.
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