Biosynthesis of hydrocarbons by algae: Decarboxylation of stearic acid to N-heptadecane inAnacystis nidulans determined by(13)C- and(2)H-labeling and(13)C nuclear magnetic resonance.

The distribution of isotopic labels inn-heptadecane enriched from [1,2-(13)C] and [2-(13)C, 2-(2)H3) acetates byAnacystis nidulans has been determined by(13)C nuclear magnetic resonance ((13)C NMR). Labeling with [1,2-(13)C] acetate is consistent with assembly from(13)C-(13)C units derived from an acetate "starter" group and 8 malonate units, as in fatty acid biosynthesis, followed by production of a methyl group through bond cleavage of the terminal(13)C-(13)C unit. A comparison of the hydrocarbon with palmitic acid (the only fatty acid produced in sufficient amount for NMR analysis) enriched from [2-(13)C,2-(2)H3]acetate by the same culture shows that they have retained the same fraction of(2)H at corresponding sites, and have therefore undergone identical biosynthetic and hydrogen-deuterium exchange processes, as would be expected ifn-heptadecane originates from de novo-synthesized stearic acid.