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How light-induced charge transfer accelerates the receptor-state recovery of photoactive yellow protein from its signaling state.

ABSTRACT: Stark (electroabsorption) spectra of the M100A mutant of photoactive yellow protein reveal that the neutral, cis cofactor of the pB intermediate undergoes a strikingly large change in the static dipole moment (|Deltamu| = 19 Debye) on photon absorption. The formation of this charge-separated species, in the excited state, precedes the cis --> trans isomerization of the pB cofactor and the regeneration of pG. The large |Deltamu|, reminiscent of that produced on the excitation of pG, we propose, induces twisting of the cis cofactor as a result of translocation of negative charge, from the hydroxyl oxygen, O1, toward the C7-C8 double bond. The biological significance of this photoinduced charge transfer reaction underlies the significantly faster regeneration of pG from pB in vitro, on the absorption of blue light.

SUBMITTER: Premvardhan L

PROVIDER: S-EPMC1367008 | biostudies-other | 2005 Dec

REPOSITORIES: biostudies-other

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How light-induced charge transfer accelerates the receptor-state recovery of photoactive yellow protein from its signaling state.

Premvardhan L L van der Horst M A MA Hellingwerf K J KJ van Grondelle R R

Biophysical journal 20051028 6

Stark (electroabsorption) spectra of the M100A mutant of photoactive yellow protein reveal that the neutral, cis cofactor of the pB intermediate undergoes a strikingly large change in the static dipole moment (|Deltamu| = 19 Debye) on photon absorption. The formation of this charge-separated species, in the excited state, precedes the cis --> trans isomerization of the pB cofactor and the regeneration of pG. The large |Deltamu|, reminiscent of that produced on the excitation of pG, we propose, i ...[more]

PMID: 16258045

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