MOLTEN GLOBULE OF CYTOCHROME-C STUDIED BY SMALL-ANGLE X-RAY-SCATTERING
MOLTEN GLOBULE OF CYTOCHROME-C STUDIED BY SMALL-ANGLE X-RAY-SCATTERING
复制标题
DOI：
10.1006/jmbi.1993.1064
复制
发表时间：
1993-02-05
影响因子：
5.6
通讯作者：
GOTO, Y
中科院分区：
文献类型：
--
作者：
KATAOKA, M;HAGIHARA, Y;GOTO, Y
小角度X射线散射技术的最新进展使得在相对较短的时间内获得关于溶液中蛋白质结构的空间分布的信息成为可能，例如分子的回转半径和形状。本文用小角X射线散射研究了马铁细胞色素的各种构象状态。而Guinier图显示熔融球态的回转半径略大于天然状态的回转半径，Kratky图显示它们的形状是球形的。为了阐明熔融球状态的形成机制，我们测量，通过小角X-射线散射，在pH 2的平衡过渡，从酸展开状态的熔融球状态，这是诱导通过添加NaCl或乙酰化赖氨酰氨基。Kratky图在不同阶段的折叠显示isoscattering点，强烈建议两个国家的机制。对于NaCl和乙酰化诱导的转变，从Kratky图确定的转变曲线与远紫外圆二色性，色氨酸荧光和Soret吸收的转变曲线吻合良好，进一步支持了两态机制。
Recent advances in the small angel X-ray scattering technique have made it possible to obtain information on the spatial distribution of protein structure in solution, such as the radius of gyration and shape of the molecule, in a relatively short time. We have studied the various conformational states of horse ferricytochromecby small angle X-ray scattering. Whereas Guinier plots showed that the radius of gyration of the molten globule state is slightly larger than that of the native state, Kratky plots indicated that their shape is globular. To clarify the mechanism of the formation of the molten globule state, we measured, by the small angle X-ray scattering, the equilibrium transition at pH 2 from the acid-unfolded state to the molten globule state, which was induced either by the addition of NaCl or the acetylation of lysyl amino groups. The Kratky plots at various stages of folding showed an isoscattering point, strongly suggesting a two-state mechanism. For both the NaCl and acetylation-induced transitions, the transition curve determined from Kratky plots agreed well with the transition curves from far-ultraviolet circular dichroism, tryptophan fluorescence, and Soret absorption, further supporting the two-state mechanism.