Reversible changes in the ATPase activity and in the regulatory light chain content upon heat (30 degrees C)-treatment of "Akazara" striated adductor myosin.
Myosin from striated adductor muscle of "Akazara" scallop was incubated at 30 degrees C for 5 min in a medium containing 2 mM MgCl2 and various concentrations of Ca2+ ions. It was observed that the 30 degrees C-treatment resulted in a decrease in the Ca2+-sensitivity of myosin-ATPase as well as in the release of the regulatory light chain (EDTA-LC) of myosin. The 30 degrees C-treated myosin was then subjected to a cooling treatment, being kept for 18 h at 0 degrees C. It was found that EDTA-LC recombined with myosin and that Ca2+-sensitivity of myosin-ATPase was restored. It was also found that Ca2+ alone was about 70 times more effective than Mg2+ alone in preventing the heat-induced release of EDTA-LC from occurring and also in recombination of EDTA-LC with the heat-treated myosin.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003080:Cold Temperature; D006358:Hot Temperature; D008274:Magnesium / Q000378:metabolism; D008974:Mollusca; D009218:Myosins / Q000378:metabolism*
D000251:Adenosine Triphosphatases; D009218:Myosins; D008274:Magnesium; D002118:Calcium