Title
Oxygen Evolution in the Absence of the 33-Kilodalton Manganese-Stabilizing Protein
Document Type
Article
Publication Date
2-1-1992
Abstract
There has been a considerable amount of controversy concerning the ability of photosystem II to evolve oxygen in the absence of the 33-kDa, manganese-stabilizing protein. Early reports indicated that some capacity for oxygen evolution existed in manganese-stabilizing protein-depleted membranes while more recent studies have suggested that the observed oxygen evolution activity arose from residual manganese-stabilizing protein present in the salt-washed preparations. In this paper, it is conclusively demonstrated that significant rates of steady-state oxygen evolution are observed in oxygen-evolving photosystem II membranes in the absence of detectable quantities of the manganese-stabilizing protein. More then 99% of the manganese-stabilizing protein was removed by either one CaCl2or two NaCl-urea washes. The amount of manganese-stabilizing protein removed was quantified immunologically using mouse polyclonal antibodies. Oxygen evolution rates of 115-140 µmol of O2(mg of Chi)-1h-1were observed in the NaCl-urea-washed preparations. These rates represent about 24% of the rate observed in untreated membranes [450-600 µmol of O2(mg of Chi)-1h-1]. Somewhat lower, although still significant rates were observed in the CaCl2-washed preparations. Optimal rates of oxygen-evolving activity in NaCl-urea-washed membranes which are devoid of the manganese-stabilizing protein required high concentrations of calcium and chloride. © 1992, American Chemical Society. All rights reserved.
Publication Source (Journal or Book title)
Biochemistry
First Page
4623
Last Page
4628
Recommended Citation
Bricker, T. (1992). Oxygen Evolution in the Absence of the 33-Kilodalton Manganese-Stabilizing Protein. Biochemistry, 31 (19), 4623-4628. https://doi.org/10.1021/bi00134a012