Electric-field-induced Schiff-base deprotonation in D85N mutant bacteriorhodopsin.
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منابع مشابه
Electric-field-induced Schiff-base deprotonation in D85N mutant bacteriorhodopsin.
The application of an external electric field to dry films of Asp-85-->Asn mutant bacteriorhodopsin causes deprotonation of the Schiff base, resulting in a shift of the optical absorption maximum from 600 nm to 400 nm. This is in marked contrast to the case of wild-type bacteriorhodopsin films, in which electric fields produce a red-shifted product whose optical properties are similar to those ...
متن کاملElectric-field induced pK-changes in bacteriorhodopsin.
Bacteriorhodopsin, the only protein of the purple membranes of halobacteria [ 11, acts as a light-driven proton pump, translocating protons from the inner to the outer side of the plasma membrane [2]. The lightinduced asymmetric proton distribution contributes to the membrane potential by up to lo-40 mV [3]. Assuming a membrane thickness of 50 A, this potential difference corresponds to an elec...
متن کاملTwo groups control light-induced Schiff base deprotonation and the proton affinity of Asp85 in the Arg82 his mutant of bacteriorhodopsin.
Arg(82) is one of the four buried charged residues in the retinal binding pocket of bacteriorhodopsin (bR). Previous studies show that Arg(82) controls the pK(a)s of Asp(85) and the proton release group and is essential for fast light-induced proton release. To further investigate the role of Arg(82) in light-induced proton pumping, we replaced Arg(82) with histidine and studied the resulting p...
متن کاملDeprotonation of lipid-depleted bacteriorhodopsin.
The removal of 75% of the lipid from bacteriorhodopsin caused the following: (i) decreased efficiency and rate of deprotonation of the protonated Schiff base (as monitored by absorption of the M412 intermediate); (ii) increased efficiency of deprotonation of deionized samples; (iii) a decrease by 1 unit in the pH at which deprotonation ceases; (iv) increased intensity of Eu3+ emission in Eu3+-r...
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...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 1996
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.93.21.11618