T. Hoshino et al., STUDIES ON THE BIOSYNTHESIS OF VIOLACEIN .4. A NEW METABOLITE OF TRYPTOPHAN, CHROMOPYRROLIC ACID, PRODUCED BY CHROMOBACTERIUM-VIOLACEUM, Bioscience, biotechnology, and biochemistry, 57(5), 1993, pp. 775-781
In order to trap the biosynthetic intermediate of violacein, a number
of mutants were prepared. A novel tryptophan metabolite was produced b
y the administration of tryptophan to washed whole cells of the mutant
of Chromobacterium violaceum. The chemical structure was determined t
o be 3,4-di-(3-indolyl)-pyrrole 2,5-dicarboxylic acid on the bases of
H-1 and C-13-NMR spectra, and MS data. This compound was named chromop
yrrolic acid, and was also detected in the various metabolites produce
d by the parent strain, although the amount produced was somewhat smal
ler. The structure of chromopyrrolic acid was closely related to that
of violacein and deoxyviolacein. The pyrrole dicarboxylic acid moiety
of chromopyrrolic acid was biosynthesized by condensation reactions of
the tryptophan side chains of two tryptophan molecules, as was found
in the biosynthesis of violacein. However, the 1,2-shift of the indole
ring that was found in the biosynthesis of violacein did not occur. T
o confirm whether or not chromopyrrolic acid was a biosynthetic interm
ediate, a feeding experiment with radiolabeled chromopyrrolic acid was
carried out. The incorporation into violacein analogues failed, indic
ating that chromopyrrolic acid was produced independently of violacein
biosynthesis.