Tellam R
Biochemistry. 1985 Jul 30;24(16):4455-60. doi: 10.1021/bi00337a029.
The CaCl2 concentration dependence of the rate of actin filament elongation and of the actin monomer concentration at steady state with actin polymer (the critical actin concentration) has been investigated. A relative rate of actin filament elongation from actin polymer intermolecularly cross-linked with N,N'-p-phenylenebis(maleimide) showed a sigmoidal dependence on the concentration of CaCl2 used to induce actin polymerization. This result is shown to be consistent with a model in which only actin monomer containing five equivalently bound Ca2+ ions (Ka = 2 mM-1) is capable of addition to actin polymer. A relative dissociation rate constant for actin monomer removal from polymer was calculated from the product of the critical actin concentration and the relative elongation rate constant and was found to be virtually independent of CaCl2 concentration. The relationship between Ca2+ binding sites on actin and the CaCl2 concentration dependence of the kinetics of actin filament elongation is discussed.
研究了氯化钙浓度对肌动蛋白丝伸长速率以及肌动蛋白聚合物稳态下肌动蛋白单体浓度（临界肌动蛋白浓度）的依赖性。与N，N'-对亚苯基双马来酰亚胺分子间交联的肌动蛋白聚合物的肌动蛋白丝相对伸长速率对用于诱导肌动蛋白聚合的氯化钙浓度呈S形依赖性。结果表明，该结果与仅含五个等效结合Ca2+离子（Ka = 2 mM-1）的肌动蛋白单体能够添加到肌动蛋白聚合物中的模型一致。从临界肌动蛋白浓度和相对伸长速率常数的乘积计算出肌动蛋白单体从聚合物中去除的相对解离速率常数，发现其实际上与氯化钙浓度无关。讨论了肌动蛋白上Ca2+结合位点与肌动蛋白丝伸长动力学的氯化钙浓度依赖性之间的关系。
