JULIÁNNA SZAKÁCS*, MELINDA LAKATOS**, CONSTANŢA GANEA***, GY. VÁRÓ**

*Department of Biophysics, University of Medicine and Pharmaceutics, 540139 Tg. Mureş, Romania
**Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, Szeged, H6726, Hungary
***Department of Biophysics, “Carol Davila” University of Medicine and Pharmaceutics, 050474 Bucharest, Romania

Abstract. The proton transporting photocycle of the proteorhodopsin at its normal pH (9.5) shows a marked deuterium effect. It was shown earlier that the intermediates N and PR’ are responsible for the proton uptake and release. By proton-deuteron exchange the M2-N and N-PR’ transitions become 2–3 times slower. On the contrary, the early μs domain is less affected than the decay part of the photocycle. The effects measured on proteorhodopsin are very similar to those measured on bacteriorhodopsin.

Corresponding author’s e-mail: szjulianna@yahoo.com

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