Seeliger A G, Kurreck J, Renger G
Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Technische Universität Berlin, Germany.
Biochemistry. 1997 Mar 4;36(9):2459-64. doi: 10.1021/bi962302c.
The characteristic period four oscillation patterns of oxygen evolution induced by a train of single-turnover flashes were measured as a function of temperature in dark-adapted photosystem II (PS II) membrane fragments that were reconstituted with native plastoquinone-9 (PQ-9) by a recently developed procedure [Kurreck, J., Seeliger, A. G., Reifarth, F., Karge, M., & Renger, G. (1995) Biochemistry 34, 15721-15731]. The following results were obtained: (a) within the range 0-35 degrees C, the probabilities of misses (alpha) and double-hits (beta) and the dark population of redox state S1 exhibit similar dependencies on the temperature; (b) below a characteristic temperature theta(c) these parameters remain virtually independent of temperature, above theta(c) (theta(c) = 20 degrees C for alpha and beta; theta(c) = 30 degrees C for S1) the values of alpha and beta increase whereas S1 decreases; and (c) the dark decay of S2 and S3 via fast and slow kinetics owing to reduction of the water oxidase by Y(D) and other endogenous electron donor(s), respectively, exhibits comparatively strong temperature dependencies with the following activation energies: E(A)(S2(fast)) = 60 +/- 10 kJ/mol, EA(S3(fast)) = 55 +/- 10 kJ/mol, E(A)(S2(slow)) = 80 +/- 5 kJ/mol, and E(A)(S3(slow)) = 75 +/- 5 kJ/mol. These values of PQ-9 reconstituted PS II membrane fragments are very similar to those that were previously reported for thylakoids [Messinger, J., Schröder, W. P., & Renger, G. (1993) Biochemistry 32, 7658-7668]. These findings reveal that the reaction coordinates of feeding electrons by endogenous electron donors into the water oxidizing complex (WOC) that attains the redox states S2 and S3 is virtually invariant to Triton X-100 treatment used in the isolation procedure of PS II membrane fragments from thylakoids. Implications of these findings are discussed.
通过最近开发的程序，用天然质体醌 - 9（PQ - 9）重构暗适应的光系统II（PS II）膜片段，测量了由一系列单周转闪光诱导的氧气释放的特征性四周期振荡模式随温度的变化。得到以下结果：（a）在0 - 35摄氏度范围内，漏击概率（α）和双击概率（β）以及氧化还原态S1的暗态群体对温度呈现相似的依赖性；（b）在特征温度θc以下，这些参数实际上与温度无关，在θc以上（α和β的θc = 20摄氏度；S1的θc = 30摄氏度），α和β的值增加而S1减小；（c）S2和S3通过快速和慢速动力学的暗态衰减，分别归因于Y（D）和其他内源性电子供体对水氧化酶的还原，表现出相对较强的温度依赖性，具有以下活化能：E(A)(S2(fast)) = 60 ± 10 kJ/mol，EA(S3(fast)) = 55 ± 10 kJ/mol，E(A)(S2(slow)) = 80 ± 5 kJ/mol，和E(A)(S3(slow)) = 75 ± 5 kJ/mol。这些PQ - 9重构的PS II膜片段的值与先前报道的类囊体的值非常相似[Messinger, J., Schröder, W. P., & Renger, G. (1993) Biochemistry 32, 7658 - 7668]。这些发现表明，在内源性电子供体将电子馈入达到氧化还原态S2和S3的水氧化复合物（WOC）的反应坐标，对于从类囊体分离PS II膜片段的过程中使用的Triton X - 100处理实际上是不变的。讨论了这些发现的意义。
