Anion binding to the Schiff base of the bacteriorhodopsin mutants Asp-85—-Asn/Asp-212—-Asn and Arg-82—-Gln/Asp-85—-Asn/Asp-212—-Asn.
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منابع مشابه
Locations of Arg-82, Asp-85, and Asp-96 in helix C of bacteriorhodopsin relative to the aqueous boundaries.
The amino acids Asp-96, Asp-85, and Arg-82, which are important for proton transport by bacteriorhodopsin, are located in helix C. Site-directed spin labeling has been used to map their positions relative to the aqueous boundaries of the membrane. Selected amino acids in helix C, in the B-C loop on the extracellular side, and in the C-D loop on the intracellular side of the membrane were replac...
متن کاملAspartic acid 85 in bacteriorhodopsin functions both as proton acceptor and negative counterion to the Schiff base.
In bacteriorhodopsin Asp85 has been proposed to function both as a negative counterion to the Schiff base and as proton acceptor in the early stages of the photocycle. To test this proposal further, we have replaced Asp85 by His. The rationale for this replacement is that although His can function as a proton acceptor, it cannot provide a negative charge at residue 85 to serve as a counterion t...
متن کاملThermodynamics of hydrogen cyanide and hydrogen fluoride binding to cytochrome c peroxidase and its Asn-82-->Asp mutant.
The thermodynamics of binding of fluoride and cyanide to cytochrome c peroxidase (CCP) and its Asn-82-->Asp mutant (D82CCP) in phosphate and acetate buffer at an ionic strength of 0.15 mol.kg-1 from pH 5.0 to 7.1 were investigated by titration calorimetry at 289 and 297 K. The binding reactions are enthalpically driven. The fluoride-binding constants determined from the titration calorimetry re...
متن کاملProton transport by a bacteriorhodopsin mutant, aspartic acid-85-->asparagine, initiated in the unprotonated Schiff base state.
At alkaline pH the bacteriorhodopsin mutant D85N, with aspartic acid-85 replaced by asparagine, is in a yellow form (lambda max approximately 405 nm) with a deprotonated Schiff base. This state resembles the M intermediate of the wild-type photocycle. We used time-resolved methods to show that this yellow form of D85N, which has an initially unprotonated Schiff base and which lacks the proton a...
متن کاملMolecular dynamics study of bacteriorhodopsin and artificial pigments.
The structure of bacteriorhodopsin based on electron microscopy (EM) studies, as provided in Henderson et al. (1990), is refined using molecular dynamics simulations. The work is based on a previously refined and simulated structure which had added the interhelical loops to the EM model of bR. The present study applies an all-atom description to this structure and constraints to the original He...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1992
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(18)41872-8