The E1 mechanism in photo-induced beta-elimination reactions for green-to-red conversion of fluorescent proteins.
The E1 mechanism in photo-induced beta-elimination reactions for green-to-red conversion of fluorescent proteins.
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DOI：
10.1016/j.chembiol.2009.10.010
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发表时间：
2009-11
影响因子：
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通讯作者：
H. Tsutsui;H. Shimizu;H. Mizuno;N. Nukina;T. Furuta;A. Miyawaki
中科院分区：
文献类型：
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作者：
H. Tsutsui;H. Shimizu;H. Mizuno;N. Nukina;T. Furuta;A. Miyawaki
KikGR是一种荧光蛋白，经过工程设计，可以在紫外线或紫外光照射下显示绿到红的光可转换性。与Kaede和EosFP这两种天然存在的光转化蛋白类似，KikGR含有his62 - tyr63 - gly64三肽序列，该序列可形成绿色发色团，通过β的形式消除和π共轭体系的后续延伸可光转化为红色发色团。使用KikGR的可结晶变体，我们以1.55 Å分辨率确定了绿色和红色状态的结构。红色发色团中his62 - c - α和his62 - c - β之间的双键呈顺时针构型，表明在his62c - α- c - α键断裂后，沿his62c - α- c - β键发生了旋转。这种结构重排提供了证据，表明控制KikGR绿到红光转化的β-消除反应遵循E1（消除，单分子）机制。
KikGR is a fluorescent protein engineered to display green-to-red photoconvertibility that is induced by irradiation with ultraviolet or violet light. Similar to Kaede and EosFP, two naturally occurring photoconvertible proteins, KikGR contains a His62-Tyr63-Gly64tripeptide sequence, which forms a green chromophore that can be photoconverted to a red one via formal β-elimination and subsequent extension of a π-conjugated system. Using a crystallizable variant of KikGR, we determined the structures of both the green and red state at 1.55 Å resolution. The double bond between His62-Cαand His62-Cβin the red chromophore is in acisconfiguration, indicating that rotation along the His62Cα-Cβbond occurs following cleavage of the His62Nα-Cαbond. This structural rearrangement provides evidence that the β-elimination reaction governing the green-to-red photoconversion of KikGR follows an E1 (elimination, unimolecular) mechanism.