Actin binding and SH1 sulfhydryl group modification activate myosin MgATPase to a similar extent under physiological ionic strengths, providing insight into the mechanism of actin activation.
Abstract The ionic strength dependence of the absolute activation of myosin MgATPase by actin binding or by chemical modification of the SH1 sulfhydryl group has been investigated. At physiological ionic strengths the extent of activation induced by the two procedures are essentially identical, but differ markedly as the ionic strength is decreased below 0.10. Similar behavior is also found for subfragment I. These findings are discussed in terms of the mechanism of actin activation of myosin MgATPase under physiological conditions.
Burke et al. (1974) studied this question.