(R)-Indoleisopropionic acid (I) [(2R)-(3-indolyl)-propionic acid], a metabolite of a Claviceps strain, is formed from l-tryptophan and the intact methyl group of l-methionine. Indoleacetic acid is not incorporated into indoleisopropionic acid. (2R,S), (3S,R)-3-methyltryptophan (β-methyltryptophan, isomer B) was efficiently incorporated, but no evidence for its formation by the organism could be obtained. A hypothetical scheme for the biosynthesis of indoleisopropionic acid is presented.
Bibliographical noteFunding Information:
1 Supported by National Institutes Grants NB 07646 and FR 05586. 2 NSF Undergraduate Summer Research ticipant, 1968.