Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
J Am Chem Soc. 2009 Oct 21;131(41):14838-43. doi: 10.1021/ja903979s.
Thiocyanate hydrolase (SCNase) is a member of a family of nitrile hydratase proteins, each of which contains a unique noncorrin cobalt center with two post-translationally modified cysteine ligands, cysteine-sulfenic acid or -sulfenate (Cys-SO(H)), and cysteine-sulfininate (Cys-SO(2)(-)), respectively. We have found that a partially matured recombinant SCNase was activated during storage. The crystal structures of SCNase before and after storage demonstrated that Cys-SO(2)(-) modification of gammaCys131 proceeded to completion prior to storage, while Cys-SO(H) modification of gammaCys133 occurred during storage. SCNase activity was suppressed when gammaCys133 was further oxidized to Cys-SO(2)(-). The correlation between the catalytic activity and the extent of the gammaCys133 modification indicates that the cysteine sulfenic acid modification of gammaCys133 is of primary importance in determining the activity of SCNase.
硫氰酸水解酶 (SCNase) 是腈水解酶蛋白家族的成员之一，每个蛋白都含有独特的非卟啉钴中心，其中包含两个经翻译后修饰的半胱氨酸配体，即半胱氨酸亚磺酸或亚硫酸酯 (Cys-SO(H)) 和半胱氨酸亚磺酰亚胺 (Cys-SO(2)(-))。我们发现部分成熟的重组 SCNase 在储存过程中被激活。储存前后 SCNase 的晶体结构表明，γCys131 的 Cys-SO(2)(-) 修饰在储存前完成，而 γCys133 的 Cys-SO(H) 修饰则发生在储存过程中。当 γCys133 进一步氧化为 Cys-SO(2)(-) 时，SCNase 活性受到抑制。γCys133 修饰程度与催化活性之间的相关性表明，γCys133 的半胱氨酸亚磺酸修饰对确定 SCNase 的活性至关重要。
