Hydrogen Bonding Controls Excited-State Decay of the Photoactive Yellow Protein Chromophore

摘要

Photoactive Yellow Protein (PYP) is believed to be the primary photoreceptor for the photoavoidance response of the salt-tolerant bacterium Halorhodospira halophila. PYP contains a deprotonated 4-hydroxy-cinnamic acid (or p-coumaric acid, pca) chromophore linked covalently to the γ-sulfur of Cys69 via a thioester bond. Upon absorbing a blue-light photon, PYP enters a fully reversible photocycle involving several intermediates on a time scale spanning from a few hundred femtoseconds to seconds.