Biosynthesis of the t-butyl group a

Biosynthesis of the t-butyl group and, thus, of pivalic acid has not yet been investigated in detail, in contrast to other branched short-chain fatty acids (Kaneda 1991). It is as-sumed that, in higher multicellular organisms, the t-butyl group, e.g., in ginkgolides, is formed by the cleavage of the C–C bond adjacent to a gem-dimethyl unit followed by methylation elicited by S-adenosylmethionine (Strømgaard and Nakanishi 2004). A similar mechanism is assumed to be responsible for the appearance of t-butyl group in the bio-synthesis of the side chain of some sterols (Giner 1993). In bacteria, one of the possible biosynthetic pathways may proceed analogously with the frequently described biosyn-thesis of branched amino acids, i.e., Val, Leu, and Ile. As noted by Bisel et al. (2008), “the possibility of t-valeryl (picolinyl) starter unit derived from Tle is very attractive for the unusual terminal t-butyl group in many compounds containing this unusual group,” but the hypothesis lacks experimental support.