BIOSYNTHESIS OF 2-METHOXY-3-ISOPROPYLPYRAZINE IN PSEUDOMONAS-PEROLENS

On the basis of the results of labeling experiments, endogenous valine, glycine, and methionine are considered to be the precursors of 2-methoxy-3-isopropylpyrazine (MIPP) produced by Pseudomonas perolens. It is postulated that the feeding of [2-C-13]pyruvate results in the labeling of C-2 and C-3 of valine and C-2 of glycine, which are subsequently incorporated into MIPP. The feeding of [3-C-13]pyruvate results in the labeling of the two methyl groups of valine, C-1 and C-2 of glycine, and the methyl group of methionine. C-13 NMR spectra of the MIPP produced by P. perolens in these feeding studies were consistent with the proposed biosynthetic route to MIPP and known metabolic pathways. Methyllabeled methionine arises from [2-C-13]glyoxylate formed from [3-C-13]pyruvate via the Krebs cycle and glyoxylate shunt.