Effect of specific mutations of tyrosine-(M)210 on the primary photosynthetic electron-transfer process in Rhodobacter sphaeroides.
Effect of specific mutations of tyrosine-(M)210 on the primary photosynthetic electron-transfer process in Rhodobacter sphaeroides.
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酪氨酸-(M)210 的特定突变对球形红杆菌初级光合电子传递过程的影响。
DOI：
10.1073/pnas.87.20.7888
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发表时间：
1990
影响因子：
11.1
通讯作者：
Schenck,C
中科院分区：
文献类型：
--
作者：
Nagarajan,V;Parson,WW;Gaul,D;Schenck,C
我们已经测量了初始电子转移过程的速率作为在光合细菌球形红细菌的本地菌株和两个突变体产生的定点诱变的反应中心的温度的函数。在突变体中，酪氨酸残基在附近的主要电子供体和受体分子被替换为苯丙氨酸或异亮氨酸。电子转移反应在突变体中较慢，并且对温度的依赖性有质的不同。在天然反应中心，速率随温度降低而增加，在苯丙氨酸突变体中，速率几乎与温度无关，而在异亮氨酸突变体中，速率随温度降低而降低。在77 K时，异亮氨酸突变体中的电子转移反应比天然的慢约30倍。这些观察结果支持了酪氨酸-（M）210在电子转移机制中起重要作用的观点。在异亮氨酸突变体中，在低温下，从激发的反应中心的受激发射经历了时间依赖性的位移到较短的波长。
We have measured the rate of the initial electron-transfer process as a function of temperature in reaction centers in a native strain of the photosynthetic bacterium Rhodobacter sphaeroides and two mutants generated by site-directed mutagenesis. In the mutants, a tyrosine residue in the vicinity of the primary electron donor and acceptor molecules was replaced by either phenylalanine or isoleucine. The electron-transfer reaction is slower in the mutants and has a qualitatively different dependence on temperature. In native reaction centers the rate increases as the temperature is reduced, in the phenylalanine mutant it is virtually independent of temperature, and in the isoleucine mutant it decreases with decreasing temperature. At 77 K, the electron-transfer reaction is approximately 30 times slower in the isoleucine mutant than in the native. These observations support the view that tyrosine-(M)210 plays an important role in the electron-transfer mechanism. In the isoleucine mutant at low temperatures, the stimulated emission from the excited reaction center undergoes a time-dependent shift to shorter wavelengths.