HUMAN CARDIAC MYOSIN LIGHT-CHAINS - SEQUENCE COMPARISONS BETWEEN MYOSIN LC1 AND LC2 FROM NORMAL AND IDIOPATHIC DILATED CARDIOMYOPATHIC HEARTS

The primary structures of light chains isolated from the human myocard ium with idiopathic dilated cardiomyopathy (IDC) were determined and c ompared with the sequence structures of myosin light chains obtained f rom control human heart myosin. Sequences were determined by chemical analysis and the identity of N-terminal residues established by mass s pectrometry. The N-terminal residues in essential (ELC) and regulatory (RLC) light chains were blocked and were identified to be trimethyl a lanine, The amino acid sequences of ELC and RLC from control human myo sin revealed a high degree of homology with those purified from rat an d chicken cardiac myosin, Comparison with a published partial chemical sequence of the human heart myosin light chains revealed significant variations, However, there was very good agreement with published sequ ences obtained by molecular biological techniques. Sequences of the li ght chains from cardiomyopathic myosin revealed no difference in the p rimary structures when compared with control human heart myosin light chains indicating IDC had no influence on, nor was caused by, altered myosin light chain gene expression.