Three rate-determining protein roles in photosynthetic O₂-evolution addressed by time-resolved experiments on genetically modified photosystems.

ABSTRACT: Light-driven water splitting by plants, algae and cyanobacteria is pivotal for global bioenergetics and biomass formation. A manganese cluster bound to the photosystem II proteins catalyzes the complex reaction at high rate, but the rate-determining factors are insufficiently understood. Here we trace the oxygen-evolution transition by time-resolved polarography and infrared spectroscopy for cyanobacterial photosystems genetically modified at two strategic sites, complemented by computational chemistry. Our results highlight three rate-determining roles of the protein environment of the metal cluster: acceleration of proton-coupled electron transfer, acceleration of substrate-water insertion after O₂-formation, and balancing of rate-determining enthalpic and entropic contributio

SUBMITTER: Mausle SM 

PROVIDER: S-EPMC12569156 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature