ATPase activities of the two cross-linked species of actin and myosin.

We describe cross-linking conditions for myosin subfragment-1 and actin with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide, with which the compositions of cross-linked species can be altered. The specific Mg-ATPase activity of cross-linked subfragment-1 in these preparations was almost the same in spite of the differences in the compositions of the cross-linked species. This suggests that the two kinds of cross-linked species have almost the same ATPase activity, and that the cross-linking at these different sites nearly equally facilitates the formation of the strong binding state which accompanies the release of ADP and Pi.