Structure, dynamics, and energetics of the primary photochemistry of photosystem II of oxygenic photosynthesis

Recent progress in two-dimensional and three-dimensional electron and X-ray crystallography of Photosystem 11 (PSII) core complexes has led to major advances in the structural definition of this integral membrane protein complex. Despite the overall structural and kinetic similarity of the PSII reaction centers to their purple nonsulfur photosynthetic bacterial homologues, the different cofactors and subtle differences in their spatial arrangement result in significant differences in the energetics and mechanism of primary charge separation. In this review we discuss some of the recent spectroscopic, structural, and mutagenic work on the primary and secondary electron transfer reactions in PSII, stressing what is experimentally novel, what new insights have appeared, and where questions of interpretation remain.