le Coutre J, Gerwert K
Lehrstuhl für Biophysik, Ruhr-Universität-Bochum, Germany.
FEBS Lett. 1996 Dec 2;398(2-3):333-6. doi: 10.1016/s0014-5793(96)01254-9.
The mechanism of the intramolecular proton transfer in the membrane protein bacteriorhodopsin (bR) is studied. The kinetic isotope effects after H/D exchange were determined for the individual photocycle reactions and used as an indicator. Significant differences in the kinetic isotope effects are observed between the intramolecular proton transfer on the release and the uptake pathways. The results suggest a fast intramolecular proton transfer mechanism in the proton release pathway, which is similar to the one proposed for ice, where the rate limiting step is the proton movement within the H bond. However, the reactions in the intramolecular proton uptake pathway occur in a mechanism similar to the one suggested for liquid water, where the rate limiting step is given by a rotational rearrangement of H bonded network groups. We propose that the experimental evidence for a proton wire mechanism given here for bacteriorhodopsin is of general relevance also for other proton transporting proteins.
对膜蛋白细菌视紫红质（bR）中分子内质子转移的机制进行了研究。通过H/D交换后确定了各个光循环反应的动力学同位素效应，并将其用作指标。在质子释放和摄取途径上的分子内质子转移之间观察到动力学同位素效应的显著差异。结果表明质子释放途径中存在快速的分子内质子转移机制，这与冰中提出的机制类似，其中限速步骤是质子在氢键内的移动。然而，分子内质子摄取途径中的反应以类似于液态水的机制发生，其中限速步骤由氢键网络基团的旋转重排给出。我们提出，这里给出的细菌视紫红质质子线机制的实验证据对其他质子转运蛋白也具有普遍意义。
