The biosynthesis of prodigiosin, the tripyrrylmethene pigment from Bacillus prodigiosus (Serratia marcescens)

Abstract

Methods were evolved for the isolation of prodigiosin and of bacterial cell residues suitable for isotopic analysis. The absorption spectrum of prodigiosin in various solvents was studied quantitatively, and the existence of 2 spectral forms depending upon the pH of the solvent demonstrated. In acid chloroform, prodigiosin has a band at 535-540 m[mu]. with [epsilon] = 110,000 [plus or minus] 5000. A comparison was made of the spectral properties of prodigiosin and of a tripyrrylmethene synthesized by Fischer and Gangl (1940). This comparison supports the tripyrrylmethene structure assigned to prodigiosin by Wrede and Rothhaas (1934). Both the nitrogen and alpha-carbon atoms of glycine are utilized specifically and to the same extent with a high degree of efficiency in the biosynthesis of prodigiosin. The carboxyl C atom of glycine is not utilized. All 3 N atoms of prodigiosin must be derived from glycine. Both C atoms of acetate are utilized specifically and to about the same extent in the biosynthesis of prodigiosin. The N of DL-leucine and of ammonium salts is incorporated into prodigiosin to the same extent as into the bacterial protein. The expts. recorded show a striking similarity between the modes of synthesis of prodigiosin and porphyrin pigments but offer no conclusive evidence relative to the participation of a tripyrrylmethene intermediate in the formation of the porphyrin ring.