Purified myosin from the spiny lobster was analyzed for enzymatic properties.
The ATPase activity of lobster myosin was enhanced by Ca2+ and EDTA, and was in-hibited by Mg2+ and TBS. Modes of effect of these and some other modifiers on the ATPase activity of this myosin were essentially the same as for rabbit myosin. In addition, Ca2+-ATPase activity of the lobster myosin decreased nearly proportionally with increasing KCl concentration, as in the case of rabbit myosin.
On the other hand, the pH -activity curve of this myosin showed two maxima, around pH 6 and 8, and both maxima were shifted to about pH 7 and 8.5-9 in the presence of Ca2+. In these respects as well as in exhibiting generally low ATPase activity under various conditions, spiny lobster myosin was more comparable with scallop myosin than with rabbit myosin.