Transient spectroscopy of bacterial rhodopsins with an optical multichannel analyzer. 2. Effects of anions on the halorhodopsin photocycle

L. Zimányi, Janos K. Lanyi

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We find that the photocycle of halorhodopsin (HR) in the presence of nitrate (but not chloride) consists of two parallel series of reactions. The first is essentially the same as that which occurs in the presence of chloride: HR →hv HRK → HRKL → HRL ↔ HRO → HR. The second photocycle, however, which we describe as HR →hv HK′K → HRKO → HRO → HR, seems characteristic of what one would observe in the absence of chloride. Absorption spectra are calculated for all species but HRK and HR′K which occur at shorter times (KO → HRO → HRL can be observed. Thus, HRO must be common to the two photocycles. Kinetic fitting of the time dependence of HRL and HRO at different chloride concentrations provides evidence for the participation of chloride in the interconversion of HRL and HRO. The results are consistent with a model in which the photoreaction is influenced by the binding of an anion (either chloride or nitrate) to site II in HR: when an anion is bound the HRK-initiated HRL-type photocyle is observed, but when the site is not occupied, the HR′K-initiated HRO-type photocycle is seen.

Original languageEnglish
Pages (from-to)5172-5178
Number of pages7
JournalBiochemistry
Volume28
Issue number12
Publication statusPublished - 1989

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Microbial Rhodopsins
Halorhodopsins
Anions
Chlorides
Spectrum Analysis
Spectroscopy
Nitrates
Absorption spectra
Kinetics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Transient spectroscopy of bacterial rhodopsins with an optical multichannel analyzer. 2. Effects of anions on the halorhodopsin photocycle. / Zimányi, L.; Lanyi, Janos K.

In: Biochemistry, Vol. 28, No. 12, 1989, p. 5172-5178.

Research output: Contribution to journalArticle

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