利用高压吸收光谱研究蛋白质结构的变化

蛋白质的结构会在压强的作用下发生变化,结构的变化会引起吸收光谱的变化。对血红素类蛋白质,这种变化主要体现在第III带,即通过观察测量第III带吸收谱的强度可以将蛋白质结构变化与压强联系起来。研究了肌红蛋白在水和甘油与水的混合液中两种情况下的第III带及Q带吸收光谱随压强(最高至7kbar)的变化关系,表明在一定范围内(水溶液中约小于2.5k-bar,甘油与水的混合液中约小于4.5kbar),Fe2 原子与血红素辅基的间距随压强的增加而线性减小;当压强超过某值后,第III带强度发生了跃迁,蛋白质发生了明显的变性。继续增加压强,肌红蛋白溶液的吸收谱则失去了肌红蛋白的基本特征。

Study of the variation of proteins structure from absorption spectrum under high pressure

The structure of proteins may be changed under high pressure. The changed structure leads to the variation of absorption spectrum. To heme proteins, the variation is connected with the intensity of Band III. The Q-band and Band III spectrum of deoxy-myoglobin in water, mixture of water with glycerol(50%:50%, v/v) are measured under pressures up to 7 kbar. It is indicated that the Fe2 to porphyrin distance changes linearly with pressure under 2.5 kbar for Tris buffer, or under 4.5 kbar for glycerol:water. Above the specified pressure, the intensity of band III has a transition which suggests the protein is denatured. When the pressure is increased more higher, spectrum of band III becomes featrureless.