Dissociation of the actin.subfragment 1 complex by adenyl-5'-yl imidodiphosphate, ADP, and PPi.
Dissociation of the actin.subfragment 1 complex by adenyl-5'-yl imidodiphosphate, ADP, and PPi.
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腺苷基-5-基亚胺二磷酸、ADP 和 PPi 解离肌动蛋白亚片段 1 复合物。
DOI：
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发表时间：
1980
影响因子：
4.8
通讯作者：
E. Eisenberg
中科院分区：
文献类型：
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作者：
L. Greene;E. Eisenberg
用紫外光学分析超离心法研究了腺苷-5 '-酰亚氨基二磷酸（AMP-PNP）、ADP和PPi解离肌动蛋白-肌球蛋白亚片段1（S-1）复合物的能力。在μ = 0.22 M，pH 7.0，22 ℃，存在饱和核苷酸的情况下，ADP使S-1与肌动蛋白的结合减弱约40倍（K等于10（5）M-1），而AMP-PNP和PPi均使结合减弱约400倍（K等于10（4）M-1）。与ADP相比，AMP-PNP和PPi的这种强10倍的解离作用与我们的数据相关，该数据显示AMP-PNP和PPi与S-1的结合比ADP的结合强约10倍。相比之下，ADP、AMP-PNP和PPi与acto.S-1的结合常数几乎相同（K等于5 × 10（3）M-1）。在4 ℃时，AMP-PNP的解离作用仅比ADP强3倍，同样，我们的数据表明AMP-PNP和ADP与S-1的结合在4 ℃时非常相似。因此，AMP-PNP和PPi是比ADP稍好的解离剂，但这三种配体之间的差异相当小。这些数据还表明，肌动蛋白和核苷酸结合到S-1上分离但相互作用的位点上，S-1分子沿着F-肌动蛋白丝独立结合，在22 ℃和生理离子强度下结合常数约为1 × 10（7）M-1。
The ability of adenyl-5'-yl imidodiphosphate (AMP-PNP), ADP, and PPi to dissociate the actin.myosin subfragment 1 (S-1) complex was studied using an analytical ultracentrifuge with UV optics, which enabled the direct determination of the dissociated S-1. At mu = 0.22 M, pH 7.0, 22 degrees C, with saturating nucleotide present, ADP weakens the binding of S-1 to actin about 40-fold (K congruent to 10(5) M-1), while both AMP-PNP and PPi weakens the binding about 400-fold (K congruent to 10(4) M-1). This 10-fold stronger dissociating effect of AMP-PNP and PPi compared to ADP correlates with our data showing that the binding of AMP-PNP and PPi to S-1 is about 10-fold stronger than the binding of ADP. In contrast, the binding constants of ADP, AMP-PNP, and PPi to acto.S-1 are nearly identical (K congruent to 5 x 10(3) M-1). At 4 degrees C, AMP-PNP has only a 3-fold stronger dissociating effect than ADP and, similarly, our data suggest that the binding of AMP-PNP and ADP to S-1 is quite similar at 4 degrees C. AMP-PNP and PPi are, therefore, somewhat better dissociating agents than ADP, but the difference among these three ligands is quite small. These data also show that actin and nucleotide bind to separate but interacting sites on S-1 and that the S-1 molecules bind independently along the F-actin filament with a binding constant of about 1 x 10(7) M-1 at 22 degrees C and physiological ionic strength.