Hamada D, Segawa S, Goto Y
Department of Biology, Graduate School of Science, Osaka University, Japan.
Nat Struct Biol. 1996 Oct;3(10):868-73. doi: 10.1038/nsb1096-868.
It is generally assumed that folding intermediates contain partially formed native-like secondary structures. However, if we consider the fact that the conformational stability of the intermediate state is simpler than that of the native state, it would be expected that the secondary structures in a folding intermediate would not necessarily be similar to those of the native state. beta-Lactoglobulin is a predominantly beta-sheet protein, although it has a markedly high intrinsic preference for alpha-helical structure. We have studied the refolding kinetics of bovine beta-lactoglobulin using stopped-flow circular dichroism and find that a partly alpha-helical intermediate accumulates transiently before formation of the native beta-sheets. The present results suggest that the folding reaction of beta-lactoglobulin follows a non-hierarchical mechanism, in which non-native alpha-helical structures play important roles.
一般认为折叠中间体包含部分形成的类似天然的二级结构。然而，如果我们考虑到中间态的构象稳定性比天然态的构象稳定性更简单这一事实，那么可以预期折叠中间体中的二级结构不一定与天然态的二级结构相似。β-乳球蛋白主要是一种β-折叠蛋白，尽管它对α-螺旋结构有明显较高的内在偏好。我们使用停流圆二色性研究了牛β-乳球蛋白的重折叠动力学，发现部分α-螺旋中间体在天然β-折叠形成之前会短暂积累。目前的结果表明，β-乳球蛋白的折叠反应遵循一种非层级机制，其中非天然的α-螺旋结构起着重要作用。
