Abstract
Kinetics were determined for the four transients K590, L540, M410, O660 of the photochemical cycle of bacteriorhodopsin (BR570) both in 1H2O and in 2H2O over a wide temperature range. Breaks in the Arrhenius plots, observed at 25‡-32‡ for the longest-lived transients coincide with a transition point in the microviscosity of the membrane as measured by depolarization of an added fluorescent probe. The earliest isotope effect occurs in the decay of L540, and is present in the subsequent formation and decay of M410 and O660. Thus in the light-driven proton pump of BR570, proton ejection from the Schiff base correlates with decay of L504 and reprotonation occurs with the decay of both M410 and O660 back to BR570.
Original language | English |
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Pages (from-to) | 267-276 |
Number of pages | 10 |
Journal | Biophysics of Structure and Mechanism |
Volume | 2 |
Issue number | 3 |
DOIs | |
State | Published - Sep 1976 |
Externally published | Yes |
Keywords
- Bacteriorhodosin
- Energy of activation
- Isotope effects
- Microviscosity
- Photochemistry