The photophobic receptor from Natronobacterium pharaonis:: Temperature and pH dependencies of the photocycle of sensory rhodopsin II
The photophobic receptor from Natronobacterium pharaonis:: Temperature and pH dependencies of the photocycle of sensory rhodopsin II
复制标题
DOI：
10.1016/s0006-3495(98)77588-5
复制
发表时间：
1998-08-01
影响因子：
3.4
通讯作者：
Engelhard, M
中科院分区：
文献类型：
--
作者：
Chizhov, I;Schmies, G;Engelhard, M
本文报道了N.通过改变测量波长、温度和pH，以及通过用D2 O交换H2O来分析pharaonis。数据可以令人满意地模拟的八个指数在整个范围内的修改后的参数。动力学数据支持一个类似的模型，细菌视紫红质（BR），如果假设一个计划的不可逆的一级反应。然后可以鉴定八种动力学不同的蛋白质状态。这些状态由五种光谱上不同的物质形成。发色团状态Si在其光谱性质上对应于BR光循环的那些，即pSRII（510）（K）、pSRII（495）（L）、pSRII（400）（M）、pSRII（485）（N）和pSRII（535）（O）。与BR相比，pSRII（400）的形成速度比M状态快10倍;然而，逆反应几乎慢100倍。与BR光循环的速率常数的温度依赖性的比较表明，差异是由Δ S的变化引起的。的pSRII光循环的速率常数几乎是不敏感的pH值从9.0到5.5的变化，并显示只有一个小的H2O/D2 O的影响。这一分析支持的想法，pSRII的构象动力学控制的pSRII的光循环的动力学。
The photocycle of the photophobic receptor sensory rhodopsin II from N. pharaonis was analyzed by varying measuring wavelengths, temperature, and pH, and by exchanging H2O with D2O. The data can be satisfactorily modeled by eight exponents over the whole range of modified parameters. The kinetic data support a model similar to that of bacteriorhodopsin (BR) if a scheme of irreversible first-order reactions is assumed. Eight kinetically distinct protein states can then be identified. These states are formed from five spectrally distinct species. The chromophore states Si correspond in their spectral properties to those of the BR photocycle, namely pSRII(510) (K), pSRII(495) (L), pSRII(400) (M), pSRII(485) (N), and pSRII(535) (O). In comparison to BR, pSRII(400) is formed similar to 10 times faster than the M state; however, the back-reaction is almost 100 times slower. Comparison of the temperature dependence of the rate constants with those from the BR photocycle suggests that the differences are caused by changes of Delta S. The rate constants of the pSRII photocycle are almost insensitive to the pH variation from 9.0 to 5.5, and show only a small H2O/D2O effect. This analysis supports the idea that the conformational dynamics of pSRII controls the kinetics of the photocycle of pSRII.