Abstract
The rotational motions of F-ai HMM and S-l are equally effective, on a molar basis, in slowing this rotation and both produce their maximal effect at a ratio of about one molecule of HMM or S- 1 per ten actin monomers. With chymotryptic S-1, the effect is partially reversed at higher concentrations. With S- 1 prepared with papain in the presence of Mg2 + : the reversal is smaller, while with HMM or myosin there is no reversal at higher concentrations. Tropomyosin slightly decreases the aetin rotational mobility, and the addition of HMM to the actin-tropomyosin complex produces a further slowing. The rotational correlation time for acto-HMM is the same whether the spin-label is on actin or HMM, indicating that the rotation of the head region of HMM when bound to F-a&in is controlled by a mode of rotation within the F-actin filaments.
Published Version
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