徳島大学 教育・研究者情報データベース(EDB)

1. 徳島大学.大学院ヘルスバイオサイエンス研究部.生体情報薬科学部門.分子情報薬学講座(2004年4月1日〜)

1. 植野 哲([徳島大学.大学院医歯薬学研究部.薬学域.薬科学部門.総合薬学教育学系.総合薬学研究推進学])

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2. 柴田 瑩

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3. (英) Ayako Yorimitsu

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4. 馬場 嘉信

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5. (英) Kamo Naoki

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(英) Redox potentials of the oriented film of the wild-type, the E194Q-, E204Q- and D96N-mutated bacteriorhodopsin

(英) The redox potentials of the oriented films of the wild-type, the E194Q-, E204Q- and D96N-mutated bacteriorhodopsins (bR), prepared by adsorbing purple membrane (PM) sheets or its mutant on a Pt electrode, have been examined. The redox potentials (V) of the wild-type bR were -470 mV for the 13-cis configuration of the retinal Shiff base in bR and -757 mV for the all-trans configuration in H(2)O, and -433 mV for the 13-cis configuration and -742 mV for the all-trans configuration in D(2)O. The solvent isotope effect (DeltaV=V(D(2)O)-V(H(2)O)), which shifts the redox potential to a higher value, originates from the cooperative rearrangements of the extensively hydrogen-bonded water molecules around the protonated C=N part in the retinal Schiff base. The redox potential of bR was much higher for the 13-cis configuration than that for the all-trans configuration. The redox potentials for the E194Q mutant in the extracellular region were -507 mV for the 13-cis configuration and -788 mV for the all-trans configuration; and for the E204Q mutant they were -491 mV for the 13-cis configuration and -769 mV for the all-trans configuration. Replacement of the Glu(194) or Glu(204) residues by Gln weakened the electron withdrawing interaction to the protonated C=N bond in the retinal Schiff base. The E204 residue is less linked with the hydrogen-bonded network of the proton release pathway compared with E194. The redox potentials of the D96N mutant in the cytoplasmic region were -471 mV for the 13-cis configuration and -760 mV for the all-trans configuration which were virtually the same as those of the wild-type bR, indicating that the D to N point mutation of the 96 residue had no influence on the interaction between the D96 residue and the C=N part in the Schiff base under the light-adapted condition. The results suggest that the redox potential of bR is closely correlated to the hydrogen-bonded network spanning from the retinal Schiff base to the extracellular surface of bR in the proton transfer pathway.

1. (英) Redox potential
2. (英) Bacteriorhodopsin
3. (英) Mutant
4. (英) Shiff base
5. (英) Hydrogen-bonded network

1. (英) Article.Affiliation: Faculty of Pharmaceutical Sciences, Tokushima University, Tokushima, Japan.

2. (英) Article.PublicationTypeList.PublicationType: Journal Article

3. (英) Article.PublicationTypeList.PublicationType: Research Support, Non-U.S. Gov't