Distribution of alkali light chains in myosin: isolation of isoenzymes.

Antibodies have been isolated which are specific for the "difference peptide" unique to the alkali 1 light chain (mol wt 20 700) of chicken breast muscle myosin. When coupled to Sepharose as an immunoadsorbent, they are capable of resolving subfragment 1, heavy meromyosin, and myosin into two fractions, one rich in alkali 1 and the other rich in alkali 2. This fractionation provides direct evidence for the existence of two isoenzymic populations in vertebrate skeletal myosin. The ability of antibodies to the difference peptide to distinguish between alkali 1 and 2 provides a marker which will allow the distribution of alkali light chains in muscle fibers and filaments to be investigated.