Transient proton uptake and release is associated with the photocycle of the photoactive yellow protein from the purple phototrophic bacterium Ectothiorhodospira halophila.
Transient proton uptake and release is associated with the photocycle of the photoactive yellow protein from the purple phototrophic bacterium Ectothiorhodospira halophila.
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DOI：
10.1006/abbi.1993.1545
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发表时间：
1993-11
影响因子：
3.9
通讯作者：
Terrance E. Meyer;M. Cusanovich;Gordon Tollin
中科院分区：
文献类型：
--
作者：
Terrance E. Meyer;M. Cusanovich;Gordon Tollin
在445 nm的激光激发下，光活性黄色蛋白（PYP）在不到10 ns的时间内经历漂白和红移，在大约200微秒内经历进一步的漂白，然后在大约200毫秒内重新着色。在光漂白过程中发生构象变化，暴露疏水性位点。我们现在已经证明，这个光循环还包括在完全漂白的第二中间体形成过程中净吸收一个质子，随后在PYP返回基态时释放一个等效的质子。质子摄取略落后于PYP漂白，是一级反应，表明蛋白质构象变化分两步发生。结果表明，通常埋在蛋白质内部的碱性残基在PYP光循环期间短暂暴露于溶剂中，因此经历了pK的变化。根据PYP的晶体结构，我们提出这个碱性残基是赖氨酸111。
Upon excitation by a laser flash at 445 nm, the photoactive yellow protein (PYP) undergoes a bleach and red-shift occurring in less than 10 ns, undergoes a further bleach in approximately 200 microseconds, and then recolors in approximately 200 ms. A conformational change occurs during photobleaching which exposes a hydrophobic site. We have now shown that this photocycle also involves a net uptake of one proton during formation of the fully bleached second intermediate, followed by an equivalent proton release upon return of PYP to the ground state. Proton uptake lags slightly behind PYP bleaching and is first-order, indicating that the protein conformational change occurs in two steps. The results suggest that a basic residue which is normally buried in the protein interior is transiently exposed to solvent during the PYP photocycle and, as a consequence, undergoes a change in pK. On the basis of the crystal structure of PYP, we propose that this basic residue is lysine 111.