Studies on the biosynthesis of asperparaline A: origin of the spirosuccinimde ring system.

The primary amino acid building blocks that constitute asperparaline A have been determined through feeding and incorporation of 13C-labeled intermediates. The beta-methyl proline residue is constituted from (S)-isoleucine, the novel spiro-succinime moiety is derived from the oxidative degradation of (S)-tryptophan, and (S)-adenosylmethionine contributes the two N-methyl residues. In addition, it was found that the incorporation of 13C-labeled acetate into the single isoprene unit clearly demonstrates that the isoprene moiety is derived from the mevalonate pathway.