Opening the Schiff base moiety of bacteriorhodopsin by mutation of the four extracellular Glu side chains

Carolina Sanz, Tzvetana Lazarova, Francesc Sepulcre, Rafael González-Moreno, José Luis Bourdelande, Enric Querol, Esteve Padrós

Research output: Contribution to journalArticleResearchpeer-review

26 Citations (Scopus)

Abstract

The quadruple bacteriorhodopsin (BR) mutant E9Q+E74Q+E194Q+E204Q shows a λ(max) of about 500 nm in water at neutral pH and a great influence of pH and salts on the visible absorption spectrum. Accessibility to the Schiff base is strongly increased, as detected by the rapid bleaching effect of hydroxylamine in the dark as well as in light. Both the proton release kinetics and the photocycle are altered, as indicated by a delayed proton release after proton uptake and changed M kinetics. Moreover, affinity of the color-controlling cation(s) is found to be decreased. We suggest that the four Glu side chains are essential elements of the extracellular structure of BR. Copyright (C) 1999 Federation of European Biochemical Societies.
Original languageEnglish
Pages (from-to)191-195
JournalFEBS Letters
Volume456
Issue number1
DOIs
Publication statusPublished - 30 Jul 1999

Keywords

  • Bacteriorhodopsin
  • E9Q+E74Q+E194Q+E204Q mutant
  • Extracellular structure
  • Hydroxylamine accessibility

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