Controlling the photoreactivity of the photoactive yellow protein chromophore by substituting at the p-coumaric acid group.

ABSTRACT: We have performed ab initio CASSCF, CASPT2, and EOM-CCSD calculations on doubly deprotonated p-coumaric acid (pCA(2-)), the chromophore precursor of the photoactive yellow protein. The results of the calculations demonstrate that pCA(2-) can undergo only photoisomerization of the double bond. In contrast, the chromophore derivative with the acid replaced by a ketone (p-hydroxybenzylidene acetone, pCK(-)) undergoes both single- and double-bond photoisomerization, with the single-bond relaxation channel more favorable than the double-bond channel. The substitution alters the nature of the first excited states and the associated potential energy landscape. The calculations show that the electronic nature of the first two (π,π*) excited states are interchanged in vacuo due to the substitution.

SUBMITTER: Boggio-Pasqua M 

PROVIDER: S-EPMC3102441 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature