Proton in the well and through the desolvation barrier

Autor(en): Mulkidjanian, Armen Y.
Stichwörter: AQUEOUS ACCESS CHANNELS; bacterial flagellum; Biochemistry & Molecular Biology; Biophysics; C-RING ROTATION; chemiosmotic theory; COLI ATP SYNTHASE; CYTOCHROME BC(1) COMPLEX; ELECTRON-TRANSFER; ESCHERICHIA-COLI; FOF1-type ATP synthase; IRON-SULFUR PROTEIN; membrane transport; PHOTOSYNTHETIC REACTION-CENTER; proton transfer; Rhodobacter capsulatus; RHODOBACTER-CAPSULATUS; SECONDARY QUINONE ACCEPTOR; solvation energy
Erscheinungsdatum: 2006
Herausgeber: ELSEVIER
Volumen: 1757
Ausgabe: 5-6
Startseite: 415
Seitenende: 427
The concept of the membrane proton well was suggested by Peter Mitchell to account for the energetic equivalence of the chemical (Delta pH) and electrical (Delta psi) components of the proton-motive force. The proton well was defined as a proton-conducting crevice passing down into the membrane dielectric and able to accumulate protons in response to the generation either of Delta psi or of Delta pH. In this review, the concept of proton well is contrasted to the desolvation penalty of > 500 meV for transferring protons into the membrane core. The magnitude of the desolvation penalty argues against deep proton wells in the energy-transducing enzymes. The shallow Delta pH- and Delta psi-sensitive proton traps, mechanistically linked to the functional groups in the membrane interior, seem more realistic. In such constructs, the draw of a trapped proton into the membrane core can happen at the expense of some exergonic reaction, e.g., release of another proton from the membrane into the aqueous phase. It is argued that the proton transfer in the ATP synthase and the cytochrome bc complex could proceed in this way. (c) 2006 Elsevier B.V. All rights reserved.
14th European Bioenergetic Conference, Moscow, RUSSIA, JUL 22-27, 2006
ISSN: 00052728
DOI: 10.1016/j.bbabio.2006.04.023

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