Inactivation of Oxygen Evolution by Low pH-Treatment of Two Rice Photosystem II Preparations Containing One and Two Bound Ca2+
Ca2+ is considered to function as a cofactor of PS II electron transport . Oxygen-evolving PS II membranes prepared with Triton X-100 from higher plants contain two Ca2+ per PS II [2–4.] except for wheat preparations which have three Ca2+ per PS II . The two Ca2+ are heterogeneous in terms of their binding stability; one Ca2+ can be readily extracted by various treatments while leaving another bound to the PS II membranes [2–5]. Ono and Inoue  have shown that a brief treatment of spinach PS II membranes at pH 3.0 results in a strong in-activation of oxygen evolution with a concomitant extraction of one of the two bound Ca2+. Because the activity was substantially restored upon addition of Ca2+, they suggested that the acid-extractable Ca2+ is essential for PS II electron transport.
KeywordsOxygen Evolution Double Reciprocal Plot Mutant Complex Type Rice Chlorina Mutant
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- 3.Katoh, S., Satoh, K., Ohno, T., Shen, J.-R. and Kashino, Y. (1987) in: Progress in Photosynthesis Research (Biggins, J. ed.), Vol. I, pp. 625–628, Martinus Nijhoff, DordrechtGoogle Scholar