A 13C-NMR study of the biosynthesis of 3-methylpentacosane in the American cockroach.
13C-NMR spectrometry was used to examine the in vivo incorporation of 13C-labeled precursors into 3-methylpentacosane in the cockroach Periplaneta americana. Natural abundance 13C-NMR of 3-methylpentacosane showed that carbons 1 through 6, 23 through 25 and the branching methyl carbon (C26) each gave distinct signals, with carbons 7 through 22 indistinguishable from each other. The label from dipotassium 2-[methyl-13C]methylmalonate was incorporated primarily into the methyl branch of 3-methylpentacosane, demonstrating the 2-methylmalonate is the precursor to the methyl branch unit. The carboxyl carbon from sodium [1-13C]propionate was incorporated exclusively into the 4-position. This indicates that propionate, as a 2-methylmalonyl derivative, is incorporated as the second unit during chain synthesis rather than toward the end of the elongation process. The labeled carbon from sodium [1-13C]acetate was incorporated into carbons 2, 6 and 24 and the labeled carbon from [2-13C]acetate was incorporated into carbons 1, 5, 23 and 25 of 3-methylpentacosane, respectively. These data are consistent with an elongation-decarboxylation pathway for 3-methylpentacosane biosynthesis.
D000085:Acetates / Q000378:metabolism; D000473:Alkanes / Q000096:biosynthesis*; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D003058:Cockroaches / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008764:Methylmalonic Acid / Q000378:metabolism; D011422:Propionates / Q000378:metabolism
D000085:Acetates; D000473:Alkanes; D011422:Propionates; C010236:3-methylpentacosane; D008764:Methylmalonic Acid