The study demonstrates that a four-state model is sufficient to describe actomyosin ATPase kinetics, as the Pi burst at high actin is low.
Four-(1984), J. Biol. Chem. 259, 11908 and six-(1985) Science 227, 999 state models have been proposed for actomyosin ATPase. A key experiment in deciding between these is whether or not there is a transient Pi burst at high actin. In the first, the cleavage and release of products rates are similar and the Pi burst is low; in the second, there are additional product complexes and the Pi burst is large. We reinvestigated the problem by carrying out burst experiments under the conditions in (1985) Science 227, 999. Since we find that the Pi burst at high actin is low, we conclude that the four-state model is sufficient to describe actomyosin ATPase.
Tesi et al. (Mon,) studied this question.