Conformational Changes In Myosin Research Articles

Conformational changes in myosin under ATP hydrolysis.

During ATP hydrolysis by spin‐labelled myosin the time‐dependent local conformational changes near S1 thiol groups have been observed. In the steady‐state stage of ATP hydrolysis practically all myosin molecules are in conformationally changed state M̃. After reaction, part of the myosin molecules returns to the initial conformational state M, and another part remains in conformation M̃ forming a complex with ADP.

The conformation of myosin during the steady state of ATP hydrolysis: Studies with myosin spin labeled at the S 1 thiol groups

MgATP produces a large change in the ESR spectrum of myosin that has been spin labeled at the S 1 thiol groups. This change, indicative of increased mobility of the label, persists during the steady state of the hydrolysis of ATP, and when ATP has been depleted the spectrum changes to one identical with that observed on adding MgADP. It appears that the binding or hydrolysis of ATP by myosin in the presence of Mg induces a conformational change in myosin that persists during the steady state. If, as proposed by Taylor and coworkers (1,2) the predominant species present during the steady state is the myosin-ADP complex, then the conformation of myosin in this complex depends on whether the complex was formed with added ADP or in the course of the hydrolysis of ATP.