Chemical modification and spin-label studies of carboxyl residues in bacteriorhodopsin. [In purple membrane of Halobacterium halobium]
The structural and functional roles of carboxyl residues in bacteriorhodopsin have been investigated by amino acid chemical modification and electron paramagnetic resonance studies of spin-labeled bacteriorhodopsin. Carboxyl modification of bacteriorhodopsin using either the water-soluble reagent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, or a hydrophobic reagent, N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline, resulted in no changes in the absorption spectra or visible circular dichroism spectra, and the modified protein retained proton pumping activity. A structural role for a carboxyl residue in the bacteriorhodopsin photocycle was found by analyzing the kinetics for the decay of the M/sub 412/ intermediate. Chemical modification and spin-label studies have identified several distinct functional roles for the buried carboxyl residues of BR in the mechanism of the light-driven proton pump. In addition, these studies obtained structural information which supports current models of BR protein structure in the purple membrane.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5687927
- Report Number(s):
- LBL-16228; ON: DE83016692
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL FUNCTIONS
CARBOXYLIC ACID SALTS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED-PARTICLE TRANSPORT
ELECTRON SPIN RESONANCE
FUNCTIONS
MAGNETIC RESONANCE
MEMBRANE TRANSPORT
MEMBRANES
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
PHOTOSYNTHETIC BACTERIA
PIGMENTS
PROTEINS
PROTON TRANSPORT
RADIATION TRANSPORT
RESONANCE
RHODOPSIN