Furukawa K, Arata T
J Biochem. 1984 May;95(5):1343-8. doi: 10.1093/oxfordjournals.jbchem.a134741.
We investigated the effect of tryptic digestion of S-1 (95K) into three segments (27K, 50K, and 20K) on the binding of F-actin with S-1, using an ultracentrifugal separation method and a light-scattering method. The tryptic digestion of S-1 decreased the affinity of S-1 for F-actin both in the absence of nucleotide and the presence of AMPPNP or ATP, suggesting that the peptide cutting impairs the structures participating in the binding of S-1 or S-1-nucleotide complex with F-actin. Although nucleotides markedly weakened the affinity of S-1 for F-actin, the ratios of affinity of digested S-1 for F-actin to that of intact S-1 were all about 1/10 both in the absence and presence of nucleotides. This may be understood if we accept the assumption that two kinds of structure participate in the binding of S-1 with F-actin; one is independent of nucleotides and the other is dependent on them, with only the former being affected by the tryptic digestion of S-1.
我们采用超速离心分离法和光散射法，研究了将S-1（95K）胰蛋白酶消化成三个片段（27K、50K和20K）对F-肌动蛋白与S-1结合的影响。S-1的胰蛋白酶消化在无核苷酸以及存在AMPPNP或ATP的情况下均降低了S-1对F-肌动蛋白的亲和力，这表明肽切割会损害参与S-1或S-1-核苷酸复合物与F-肌动蛋白结合的结构。尽管核苷酸显著削弱了S-1对F-肌动蛋白的亲和力，但在无核苷酸和有核苷酸的情况下，消化后的S-1对F-肌动蛋白的亲和力与完整S-1的亲和力之比均约为1/10。如果我们接受这样的假设，即两种结构参与S-1与F-肌动蛋白的结合，一种独立于核苷酸，另一种依赖于核苷酸，且只有前者会受到S-1胰蛋白酶消化的影响，那么这一点就可以理解了。
