Denaturation of actin portion of carp myosin B induced by three polymerized phosphates (sodium pyrophosphate (PPi), sodium tripolyphosphate (TPi), sodium polyphosphate (PolyPi)) was investigated.
When 1mM PPi or TPi, or 0.03% PolyPi was added to myosin B in a medium consisting of 0.3-0.7_M KCl, 40mM Tris-maleate (pH 7.0) and 0-5.0mM MgCl₂ a change in various ATPase activities, an increase of 50mM KCl soluble actin, and liberation of inorganic phosphate (Pi) were measured as a function of time at 10°C.
Comparison of the rates and extents of actin release from myosin B and of Pi liberation from polymerized phosphate suggested that production of PPi through hydrolysis of TPi and PolyPi by myosin triphosphatase caused therelease of denatured actin from myosin B into 50mM KCL medium. As the KCL concentration of myosin B solution was increased from 0.3 to 0.7_M, the denaturation reaction of actin in myosin B was accerelated.