Author:
Downer M. C.,Islam M.,Shank C. V.,Harootunian A.,Lewis A.
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.