Diverse Transient Chiral Dynamics in Evolutionary distinct Photosynthetic Reaction Centers

Abstract

The evolution of photosynthetic reaction centers (RCs) from anoxygenic bacteria to oxygenic cyanobacteria and plants reflects their structural and functional adaptation to environmental conditions. Chirality plays a significant role in influencing the arrangement and function of key molecules in these RCs. This study investigates chirality-related energy transfer in two distinct RCs: Thermochromatium tepidum (BRC) and Thermosynechococcus vulcanus (PSII RC) using two-dimensional electronic spectroscopy (2DES). Circularly polarized laser pulses reveal transient chiral dynamics, with 2DCD spectroscopy highlighting chiral contributions. BRC displays more complex chiral behavior, while PSII RC shows faster coherence decay, possibly as an adaptation to oxidative stress. Comparing the chiral dynamics of BRC and PSII RC provides insights into photosynthetic protein evolution and function.