Distribution of alkali light chains in myosin: isolation of isoenzymes

Abstract
Antibodies were isolated which are specific for the difference peptide unique to the alkali 1 L chain (MW 20,700) of chicken breast muscle myosin. When coupled to Sepharose as an immunoadsorbent, they were capable of resolving subfragment 1, heavy meromyosin and myosin into 2 fractions, 1 rich in alkali 1 and the other rich in alkali 2. This fractionation provided direct evidence for the existence of 2 isoenzymic populations in vertebrate skeletal myosin. The ability of antibodies to the difference peptide to distinguish between alkali 1 and 2 provided a marker which allows the distribution of alkali L chains in muscle fibers and filaments to be investigated.