3-Methylhistidine in actin and other muscle proteins

Abstract

By the use of the extended elution system for basic amino acid analysis, 3-methylhistidine was detected in hydrolysates of actin isolated from mammalian, fish and bird skeletal muscle. Evidence is presented to indicate that 3-methylhistidine forms part of the primary structure and that in rabbit actin this residue is restricted to 1 peptide fraction obtained from the tryptic digest. Rabbit skeletal muscle actin has a 3-methylhistidine histidine ratio 1:7.6, indicating a minimum molecular weight of 47,600. Adult rabbit myosin contains approximately 2,3-methylhistidine residues/mol. These residues are localized in the heavy meromyosin part of the molecule, and are restricted to the major component obtained after succinylation.