Pope B, Wagner P D, Weeds A G
Eur J Biochem. 1981 Jun;117(1):201-6. doi: 10.1111/j.1432-1033.1981.tb06322.x.
Myosin isoenzymes, highly enriched in either alkali 1 or alkali 2 light chains have been prepared by light chain exchange in 4.7 M ammonium chloride, under conditions where there is minimal loss of ATPase activity. While the actin-activated ATPase measurements were complicated by a biphasic dependence on actin concentration, the two myosin isoenzymes behaved in a similar manner; at a variety of ionic strength conditions their maximum rates of ATP hydrolysis were nearly identical. Furthermore, under conditions where their Km values could be reliably determined, their apparent affinities for actin in the presence of ATP did not differ greatly. These results suggest that the presence of a particular alkali light chain does not influence the maximum rate of ATP turnover by actomyosin under ionic strength conditions approximating physiological.
通过在4.7M氯化铵中进行轻链交换，制备了在碱1或碱2轻链中高度富集的肌球蛋白同工酶，该条件下ATP酶活性的损失最小。虽然肌动蛋白激活的ATP酶测量因对肌动蛋白浓度的双相依赖性而变得复杂，但两种肌球蛋白同工酶的行为方式相似；在各种离子强度条件下，它们的最大ATP水解速率几乎相同。此外，在可以可靠测定其Km值的条件下，它们在ATP存在下对肌动蛋白的表观亲和力差异不大。这些结果表明，在接近生理的离子强度条件下，特定碱轻链的存在不会影响肌动球蛋白的最大ATP周转速率。
