与F-肌动蛋白结合的醋酸汞荧光素（FMA）的吸收光谱、荧光光谱和线性二色性光谱。二价阳离子的两种效应。

Absorption, fluorescence, and linear dichroism spectra of fluorescein mercuric acetate (FMA) bound to F-actin. Two kinds of effects of divalent cations.

作者信息

Mihashi K, Nakabayashi M, Yoshimura H, Ohnuma H

出版信息

J Biochem. 1979 Feb;85(2):359-66. doi: 10.1093/oxfordjournals.jbchem.a132341.

DOI:10.1093/oxfordjournals.jbchem.a132341

Abstract

Two kinds of F-actin were prepared; one binds magnesium at the unique divalent cation binding site of actin protomer and the other binds calcium at this site. They were designated as F(Mg)-actin and F(Ca)-actin, respectively. The binding of fluorescein mercuric acetate (FMA) to F(Mg)-actin and F(Ca)-actin was studied spectroscopically. The absorption and fluorescence spectra of bound FMA differed slightly but distinctly between F(Mg)-actin and F(Ca)-actin. Moreover, FMA bound to F(Mg)-actin showed linear dichroism in the presence of 2 mM MgCl2 (or 2mM CaCl2) in the solvent, while the dichroism was abolished by the removal of divalent cations from the solvent. In contrast, FMA bound to F(Ca)-actin did not show any appreciable linear dichroism irrespective of the presence (or absence) of divalent cations in the solvent. These results suggest that the structure of F-actin is characteristically regulated by divalent cations in a dual mode.

摘要

制备了两种F-肌动蛋白；一种在肌动蛋白原纤维独特的二价阳离子结合位点结合镁，另一种在该位点结合钙。它们分别被命名为F(Mg)-肌动蛋白和F(Ca)-肌动蛋白。用光谱法研究了荧光素汞乙酸酯(FMA)与F(Mg)-肌动蛋白和F(Ca)-肌动蛋白的结合。结合的FMA在F(Mg)-肌动蛋白和F(Ca)-肌动蛋白之间的吸收光谱和荧光光谱略有不同但明显不同。此外，在溶剂中存在2 mM MgCl2(或2 mM CaCl2)时，与F(Mg)-肌动蛋白结合的FMA显示出线性二色性，而通过从溶剂中去除二价阳离子可消除二色性。相反，无论溶剂中是否存在二价阳离子，与F(Ca)-肌动蛋白结合的FMA都没有显示出任何明显的线性二色性。这些结果表明，F-肌动蛋白的结构以双重模式由二价阳离子进行特征性调节。