Protein catalysis of the retinal subpicosecond photoisomerization in the primary process of bacteriorhodopsin photosynthesis
- Univ. of California, Los Angeles, CA (United States)
- Univ. of California, Irvine, CA (United States)
The rate of retinal photoisomerization in wild-type bacteriorhodopsin (wt bR) is compared with that in a number of mutants in which a positively charged (Arg[sup 82]), a negatively charged (Asp[sup 85] or Asp[sup 212]), or neutral hydrogen-bonding (Asp[sup 115] or Tyr[sup 185]) amino acid residue known to be functionally important within the retinal cavity is replaced by a neutral, non-hydrogen-bonding one. Only the replacements of the charged residues 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 isomerization catalysis and selectivity in wt bR by charged residues is discussed in terms of the known protein structure, and valence-bond wave functions of the ground and excited state of the retinal, and the electrostatic stabilization interactions within the retinal cavity.
- DOE Contract Number:
- FG03-88ER13828
- OSTI ID:
- 5378296
- Journal Information:
- Science (Washington, D.C.); (United States), Journal Name: Science (Washington, D.C.); (United States) Vol. 261:5123; ISSN SCIEAS; ISSN 0036-8075
- Country of Publication:
- United States
- Language:
- English
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140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AMIDES
AMINO ACID SEQUENCE
AMINO ACIDS
ARGININE
ASPARAGINE
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ISOMERIZATION
MOLECULAR STRUCTURE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
RHODOPSIN
STRUCTURE-ACTIVITY RELATIONSHIPS
VITAMIN A
VITAMINS