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首页> 外文期刊>Biochemistry >INTERACTION OF THE 33 KDA EXTRINSIC PROTEIN WITH PHOTOSYSTEM II - REBINDING OF THE 33 KDA EXTRINSIC PROTEIN TO PHOTOSYSTEM II MEMBRANES WHICH CONTAIN FOUR, TWO, OR ZERO MANGANESE PER PHOTOSYSTEM II REACTION CENTER
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INTERACTION OF THE 33 KDA EXTRINSIC PROTEIN WITH PHOTOSYSTEM II - REBINDING OF THE 33 KDA EXTRINSIC PROTEIN TO PHOTOSYSTEM II MEMBRANES WHICH CONTAIN FOUR, TWO, OR ZERO MANGANESE PER PHOTOSYSTEM II REACTION CENTER

机译：33 KDA外源蛋白与光系统II的相互作用-每个PHOTOSYSTEM II反应中心将33 KDA外源蛋白重新结合到包含四，二或零锰的光系统II膜上。

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摘要

The 33 kDa extrinsic protein of photosystem II acts to enhance oxygen evolution and to stabilize the manganese cluster at low chloride concentrations. Due to controversies concerning the stoichiometry of this protein [Miyao, M., Bi Murata, N. (1989) Biochim. Biophys. Acta 977, 315-321, versus Xu, Q., & Bricker, T. M. (1992) J. Biol. Chern. 267, 25816-25821] we have examined the rebinding of this protein to PS II membrane preparations which contain four, two, or zero manganese per photosystem II reaction center. After rebinding, immunoquantification of the 33 kDa extrinsic protein demonstrated that each of these photosystem II membrane preparations strongly bound two copies of the 33 kDa extrinsic protein per photosystem II reaction center. The first and second stoichiometric binding constants (K-a1 and K-a2) for the binding of the 33 kDa protein to PS II centers containing four manganese were 0.42 and 0.67 nM(-1), respectively. Disruption of the manganese cluster either by removal of the chloride-sensitive manganese or extraction of the manganese cluster by alkaline Tris led to a 5-6-fold decrease in K-a1 and about a 3-fold decrease in K-a2 In all cases the binding of the two copies of the 33 kDa extrinsic protein exhibited positive cooperativity with Hill coefficients ranging from 1.6 to 2.2. These findings demonstrate that damage to the manganese cluster alters the binding affinity of the 33 kDa extrinsic protein to photosystem II but does not alter the molecularity of the binding reaction.
机译：光系统II的33 kDa外在蛋白可增强氧气的释放，并在低氯化物浓度下稳定锰簇。由于有关该蛋白质的化学计量的争论[Miyao，M.，Bi Murata，N。（1989）Biochim.Biol.215：403-10]。生物物理学。 Acta 977，315-321，vs Xu，Q.，＆Bricker，T.M.（1992）J.Biol。陈267，25816-25821]，我们已经研究了该蛋白质与PS II膜制剂的重新结合，该PS II膜制剂每个光系统II反应中心含四个，两个或零个锰。重新结合后，对33 kDa外源蛋白的免疫定量分析表明，每个光系统II膜制剂均在每个光系统II反应中心牢固结合了两个拷贝的33 kDa外源蛋白。用于将33 kDa蛋白与包含四个锰的PS II中心结合的第一和第二化学计量结合常数（K-a1和K-a2）分别为0.42和0.67 nM（-1）。在所有情况下，通过除去对氯化物敏感的锰或通过碱性Tris萃取锰簇来破坏锰簇会导致K-a1降低5-6倍，而K-a2降低3倍。 33 kDa外源蛋白的两个拷贝的结合表现出正的协同作用，希尔系数在1.6到2.2之间。这些发现表明，对锰簇的破坏改变了33kDa外源蛋白对光系统II的结合亲和力，但没有改变结合反应的分子性。

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