Branched hydrocarbons, biosynthesis

Guo L., Quilici D. R, Chase J. and Blomquist G. J. (1991) Gut tract microorganisms supply the precursors for methyl-branched hydrocarbon biosynthesis in the termite, Zootermopsis nevadensis. Insect Biochem. 21, 327-333. 

A 13C NMR study of methyl-branched hydrocarbon biosynthesis in the housefly. 

Biosynthesis of methyl branched hydrocarbons of the German cockroach Blattella germanica (L.) (Orthoptera, Blattellidae). Insect Biochemistry 20 149-156. 

Charlton R. E. and Roelofs W. L. (1991) Biosynthesis of a volatile, methyl-branched hydrocarbon sex pheromone from leucine by Arctiid moths (Holomelina spp.). Arch. Insect Biochem. Physiol. 18, 81-97. 

A microsomal FAS was implicated in the biosynthesis of methyl-branched fatty acids and methyl-branched hydrocarbon precursors of the German cockroach contact sex pheromone (Juarez et al., 1992 Gu et al., 1993). A microsomal FAS present in the epidermal tissues of the housefly is responsible for methyl-branched fatty acid production (Blomquist et al., 1994). The housefly microsomal and soluble FASs were purified to homogeneity (Gu et al., 1997) and the microsomal FAS was shown to preferentially use methylmalonyl-CoA in comparison to the soluble FAS. GC-MS analyses showed that the methyl-branching positions of the methyl-branched fatty acids of the housefly were in positions consistent with their role as precursors of the methyl-branched hydrocarbons. 

Figure 8.5 Steps in the biosynthesis of methyl-branched hydrocarbons in the housefly.

Chase J., Jurenka R. J., Schal C., Halamkar P. P. and Blomquist G. J. (1990) Biosynthesis of methyl branched hydrocarbons in the German cockroach Blattella germanica (L.) (Qrthoptera, Blattellidae). Insect Biochem. 20, 149-156. 

Propionate serves several unique and important roles in insects. It is used by some insects, in very small amounts, as a precursor to homomevalonate which is an intermediate in the biosynthesis of juvenile hormone (JH) II (1,2) and probably JH I and JH 0 as well. Much larger amounts of propionate and methylmalonate are needed for the biosynthesis of methyl branched hydrocarbons which are major cuticular components in most of the approximately 100 insect species whose cuticular lipids have been examined (3-7). Until recently, there was little information available on either the source of propionate or its metabolism in insects. In mammals vitamin B 2 Is a key cofactor in propionate and methylmalonate metabolism (B—9). Recent observations that some insect species lack or contain low levels of vitamin B 2 (10)... 

Propionate is a key intermediate in JH and hydrocarbon biosynthesis In insects. It serves as a precursor for methyl branched hydrocarbons which in many insects are important compounds for communication and cuticular protection, and it is a precursor for juvenile hormone biosynthesis (JH 0, JH I and JH II). Sources of propionate have been shown to be succinate in a termite and certain amino acids such as valine in other species. 

Nelson, D. R. 1978. Long-chain methyl-branched hydrocarbons occurrence, biosynthesis, and function. Advances in Insect Physiology, 13, 1-33. 

---