Abstract

The dynamics of the photochemistry of bacteriorhodopsin have been investigated extensively.[1] Bacteriorhodopsin is a pigment closely related to visual rhodopsins which is extracted from the cell membrane of the Halobacterium halobium. It acts as a light-driven proton pump converting light energy into electrochemical energy in the form of a proton gradient across the cell membrane. In this paper we report time-resolved (Δt ~100 fsec.) spectroscopic measurements of the initial step in the photochemical cycle of light-adapted bacteriorhodopsin (bR₅₇₀), namely the transformation of bR₅₇₀ into bathobacteriorhodopsin (K₆₁₀). Our results confirm the hypothesis[2] that the ground state of K₆₁₀ forms directly from the excited state of bR₅₇₀. In addition, we present the first measurements of the influence of deuteration on the primary photochemistry at physiological temperatures.

© 1984 Optical Society of America