Amino-acid sequence of the 20 000-molecular-weight light chain of chicken gizzard-muscle myosin

The light chain fraction was separated from chicken gizzard muscle myosin. After S-carboxymethylation or performic acid oxidation, two light chain components (20 000-Mr and 17 000-Mr chains) were isolated by chromatography on a column of DEAF-cellulose in the presence of 4 M urea. Tryptic peptides of the S-carboxymethylated 20 000-Mr chain were isolated, and their sequences were determined. The alignment of these tryptic peptides in the chain was deduced from the amino acid compositions and from the partial sequences of peptic peptide of the oxidized protein. The established sequence consists of 171 amino acids and its calculated molecular weight is 19692. Comparing the sequence with those of L-2 chains from chicken and rabbit skeletal muscle myosins, 81 and 78 amino acid substitutions were recognized, respectively, including insertions and/or deletions.