Isolation and partial renaturation of proteolytic fragments of the myosin head.

Publisher Website
Google Scholar
Abstract
Methods have been devised for isolating 2 of the tryptic fragments (those termed 20K and 50K) of [rabbit] myosin subfragment 1 in pure form. Fragment 20K was examined for renaturation after removal of denaturants used in its preparation. It generated a CD [circular dichroism] spectrum corresponding to .apprx. 64% formed structure (roughly what would be expected from its amino acid sequence) and a red-shifted UV spectrum such as arises when phenylalanine and tyrosine are perturbed by structural interactions. Actin affinity of fragment 20K was tested by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide cross-linking, inhibition of the actin-activated ATPase of subfragment 1 containing L chain 3, cosedimentation with actin and light scattering; the affinity exceeded 5 .times. 106 M-1. Evidently, moiety 20K has a sovereign existence in (i.e., is a domain of) myosin subfragment 1. Evidently, fragment 50K also binds actin, but with a lesser affinity.