Betton J M, Desmadril M, Mitraki A, Yon J M
Biochemistry. 1984 Dec 18;23(26):6654-61. doi: 10.1021/bi00321a057.
The unfolding-refolding transition of horse muscle phosphoglycerate kinase induced by guanidine hydrochloride was studied under equilibrium conditions using four different signals: fluorescence intensity at 336 nm, UV difference absorbance at 286 and 292 nm, ellipticity at 220 nm, and enzyme activity. From the following arguments, we found that the process deviates from a two-state model and intermediates are significantly populated even at equilibrium: (1) the noncoincidence of the transition curves and (2) the asymmetry of the transition curve obtained from CD measurements. From these different data and the thermodynamic analysis, it was suggested that the two domains of the horse muscle phosphoglycerate kinase refold independently of one another with different equilibrium constants, the most favorable constant referring to the folding of the C-terminal domain which contains all tryptophans.
在平衡条件下，利用四种不同信号研究了盐酸胍诱导的马肌肉磷酸甘油酸激酶的去折叠-再折叠转变：336nm处的荧光强度、286和292nm处的紫外差吸光度、220nm处的椭圆率以及酶活性。基于以下论据，我们发现该过程偏离双态模型，即使在平衡状态下中间体也大量存在：（1）转变曲线不重合；（2）圆二色性测量得到的转变曲线不对称。从这些不同的数据以及热力学分析表明，马肌肉磷酸甘油酸激酶的两个结构域以不同的平衡常数彼此独立地再折叠，最有利的常数涉及包含所有色氨酸的C末端结构域的折叠。
