Following evolution of bacteriorhodopsin in its reactive excited state via stimulated emission pumping

Sanford Ruhman*, Bixue Hou, Noga Friedman, Michael Ottolenghi, Mordechai Sheves

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

New information concerning the photochemical dynamics of bacteriorhodopsin (BR) is obtained by impulsively stimulating emission from the reactive fluorescent state. Depletion of the excited-state fluorescence leads to an equal reduction in production of later photoproducts. Accordingly, chromophores which are forced back to the ground state via emission do not continue on in the photocycle, conclusively demonstrating that the fluorescent state is a photocycle intermediate. The insensitivity of depletion dynamics to the "dump" pulse timing, throughout the fluorescent states lifetime, and the biological inactivity of the dumped population suggest that the fluorescent-state structure is constant, well-defined, and significantly different than that where crossing to the ground state takes place naturally. In conjunction with conclusions from comparing the photophysics of BR with those of synthetic analogues containing "locked" retinals, present results show that large-amplitude torsion around C13=C14 is required to go between the above structures.

Original languageEnglish
Pages (from-to)8854-8858
Number of pages5
JournalJournal of the American Chemical Society
Volume124
Issue number30
DOIs
StatePublished - 31 Jul 2002

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