[A high molecular proteolysis-resistant actin fragment]

Abstract

The proteolysis-stable actin fragment (m. w. 36300 as determined by SDS polyacrylamide gel electrophoresis) was obtained by actin treatment with a non-identified bacterial protease. This fragment is larger than the trypsin-stable actin fragment and is similar to the unstable trypsin intermediate fragment. The obtained actin fragment is not polymerized, does not activate the ATPase activity of myosin and does not form a superprecipitating complex with it. Thus, the functional properties of actin are lost during the split-off of a relatively small, apparently, the N-terminal part of the polypeptide chain.