PROTEIN CATALYSIS OF THE RETINAL SUBPICOSECOND PHOTOISOMERIZATION IN THE PRIMARY PROCESS OF BACTERIORHODOPSIN PHOTOSYNTHESIS

Citation
L. Song et al., PROTEIN CATALYSIS OF THE RETINAL SUBPICOSECOND PHOTOISOMERIZATION IN THE PRIMARY PROCESS OF BACTERIORHODOPSIN PHOTOSYNTHESIS, Science, 261(5123), 1993, pp. 891-894
Citations number
52
Categorie Soggetti
Multidisciplinary Sciences
Journal title
ISSN journal
00368075
Volume
261
Issue
5123
Year of publication
1993
Pages
891 - 894
Database
ISI
SICI code
0036-8075(1993)261:5123<891:PCOTRS>2.0.ZU;2-V
Abstract
The rate of retinal photoisomerization in wild-type bacteriorhodopsin (wt bR) is compared with that in a number of mutants in which a positi vely charged (Arg82), a negatively charged (Asp85 or Asp212), or neutr al hydrogen bonding (Asp115 or Tyr185) amino acid residue known to be functionally important within the retinal cavity is replaced by a neut ral, non-hydrogen bonding one. Only the replacements of the charged re sidues reduced the photoisomerization rate of the 13-cis and all-trans isomers present in these mutants by factors of approximately 1/4 and approximately 1/20, respectively. Retinal photo- and thermal isomeriza tion catalysis and selectivity in wt bR by charged residues is discuss ed in terms of the known protein structure, the valence-bond wave func tions of the ground and excited state of the retinal, and the electros tatic stabilization interactions within the retinal cavity.