Zwitterion modulation of O(2)-evolving activity of cyanobacterial photosystem II.

ABSTRACT: Photosystem II (PSII) is the only enzyme in nature that can catalyze the challenging catalytic photooxidation of H(2)O into four protons, four electrons, and O(2). Slowing down turnover of the O(2)-evolving complex (OEC) is a plausible approach to gain mechanistic information on the reaction. However, modulating the kinetics of the reaction without perturbing the active site is a challenge. In this study, it is shown that the steady-state activity of cyanobacterial PSII is inhibited by small zwitterions, such as glycine betaine and β-alanine. We show that the binding of zwitterions is nondenaturing, is highly reversible, and results in the decrease of the rate of catalytic turnover by ∼50% in the presence of excess zwitterion. Control measurements of photoinduced electron transfer in O(2)-

SUBMITTER: Ulas G 

PROVIDER: S-EPMC2939297 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature