Biosynthesis of carnosine and related peptides by skeletal muscle cells in primary culture.

Synthesis of carnosine (beta-alanyl-L-histidine) and related dipeptides could be demonstrated in primary muscle cell cultures derived from embryonic chick pectoral muscle. After incubation with radiolabeled beta-alanine or gamma-aminobutyric acid, the radiolabeled dipeptides were isolated from the cell extracts and also in small amounts from the culture medium. The kinetics of dipeptide formation indicated that anserine (beta-alanyl-1-methylhistidine) is not formed directly by these cells but as a secondary product via the methylation of carnosine. Coinciding with the morphological differentiation of the mononucleated myoblast to form multi-nucleated myotubes, a rapid increase in beta-alanine uptake and also in dipeptide synthesis could be observed. These results demonstrate that carnosine and related peptides are not merely deposited in skeletal muscles but that they are actively synthesized by muscle cells in culture.