Grazi E, Cuneo P, Magri E, Schwienbacher C, Trombetta G
Istituto di Chimica Biologica, Università di Ferrara, Italy.
Biochemistry. 1993 Aug 31;32(34):8896-901. doi: 10.1021/bi00085a022.
The interaction of alpha-actinin from chicken gizzard with F-actin is quite complex. The apparent dissociation constant, C, increases with the increase of actin concentration according to the following expression: C = Ko + a[actin] - c[actin]5/2. At pH 7.5 and 37 degrees C, in the presence of 0.1 M KCl and 2 mM MgCl2, the dissociation constant at infinite actin dilution, Ko, is 2.17 microM. The binding of alpha-actinin to actin is related by the term a[actin] to the diffusion of actin filaments and by the term c[actin]5/2 to the crossing number concentration of the F-actin network. Especially at low actin concentration, the binding of alpha-actinin to actin is increased by gelsolin, which fragments actin filaments and increases their diffusion. The different binding isotherms of alpha-actinin to actin filaments and to actin bundles are discussed.
鸡砂囊的α-辅肌动蛋白与F-肌动蛋白的相互作用相当复杂。表观解离常数C随肌动蛋白浓度的增加而增加，符合以下表达式：C = Ko + a[肌动蛋白] - c[肌动蛋白]^(5/2)。在pH 7.5和37℃条件下，存在0.1 M KCl和2 mM MgCl2时，无限稀释肌动蛋白时的解离常数Ko为2.17 μM。α-辅肌动蛋白与肌动蛋白的结合，其中a[肌动蛋白]项与肌动蛋白丝的扩散有关，c[肌动蛋白]^(5/2)项与F-肌动蛋白网络的交叉数浓度有关。特别是在低肌动蛋白浓度下，凝溶胶蛋白可增加α-辅肌动蛋白与肌动蛋白的结合，凝溶胶蛋白可使肌动蛋白丝断裂并增加其扩散。文中讨论了α-辅肌动蛋白与肌动蛋白丝和肌动蛋白束的不同结合等温线。
