Kwon O S, Lo S C, Kwok F, Churchich J E
Department of Biochemistry, University of Tennessee, Knoxville 37996-0840.
J Biol Chem. 1993 Apr 15;268(11):7912-6.
myo-Inositol monophosphatase isolated from pig brain is a very stable dimeric protein characterized by a rotational correlation time of 30 ns. The unfolding and dissociation of the dimeric enzyme (58 kDa) by guanidine hydrochloride have been investigated at equilibrium. The overall process was reversible as judged from the complete recovery of catalytic activity after dilution of guanidine hydrochloride-treated samples. Unfolding of myo-inositol monophosphatase was monitored by circular dichroism, fluorescence, and steady state emission anisotropy. A folded, monomeric form of the monophosphatase was not detected by the method of denaturant gel filtration. Uncoupled dissociation and unfolding of the oligomeric enzyme could not be demonstrated. The circular dichroism and emission anisotropy results are consistent with a model in which the dimeric protein unfolds in a single cooperative transition from folded dimer to two unfolded monomers.
从猪脑中分离出的肌醇单磷酸酶是一种非常稳定的二聚体蛋白，其特征在于旋转相关时间为30纳秒。在平衡状态下研究了盐酸胍对二聚体酶（58 kDa）的展开和解离作用。从盐酸胍处理过的样品稀释后催化活性完全恢复这一点判断，整个过程是可逆的。通过圆二色性、荧光和稳态发射各向异性监测肌醇单磷酸酶的展开。变性剂凝胶过滤法未检测到单磷酸酶的折叠单体形式。无法证明寡聚酶的解偶联解离和展开。圆二色性和发射各向异性结果与一个模型一致，在该模型中，二聚体蛋白以单一协同转变的方式从折叠二聚体展开为两个未折叠的单体。
