The photoreceptor sensory rhodopsin I as a two-photon-driven proton pump.

Proton translocation experiments with intact cells of Halobacterium salinarium overproducing sensory rhodopsin I (SRI) revealed transport activity of SRI in a two-photon process. The vectoriality of proton translocation depends on pH, being outwardly directed above, and inwardly directed below, pH 5.7. Activation of the transport cycle requires excitation of the initial dark state of SRI, SRI590, to form the intermediate SRI380. Action spectra identify the photocycle intermediates SRI380 and SRI520 as the two photochemically reactive species in the outwardly directed transport process. As shown by flash photolysis experiments, SRI520 undergoes a so-far unknown photochemical reaction to SRI380 with a half-time of <200 micros. Mutation of SRI residue Asp-76, the residue which is equivalent to the proton acceptor Asp-85 in bacteriorhodopsin, to asparagine leads to inactivation of proton translocation. This demonstrates that the underlying mechanisms of proton transport in both retinal proteins share similar features. However, SRI is to our knowledge the first case where photochemical reactions between two thermally unstable photoproducts of a retinal protein constitute a catalytic ion transport cycle.

Site selection for the monitoring of photochemical air pollutants /

Mode of access: Internet.

Overview of the environmental control measures and problems in the food processing industries /

Mode of access: Internet.

Development and validation of methods for sampling and analysis of workplace toxic substances /

Mode of access: Internet.

Low-cost process for P-N junction-type solar cell : quarterly report 4 for May 30 - September 1, 1980 /

"Work Performed Under Contract No. AC02-77CH00178."

A guide to Panjabi.

Mode of access: Internet.

Traffic safety demonstration program modeling system. Volume III: citizens band radio model. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Traffic safety demonstration program modeling system. Volume IV: appendices.

National Highway Traffic Safety Administration, Washington, D.C.

Vedda music /

"Reprinted from The Veddas by C.G. Seligmann and Brenda Z. Seligmann. Published by the Cambridge University Press"--Cover.

Traffic safety demonstration program modeling system. Volume I: technical summary. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Satisfaction of the automotive fleet fuel demand and its impact on the oil refining industry. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Hazardous wastes : a risk-benefit framework applied to cadmium and asbestos /

SRI project no. EGU-3561 ; EPA contract no. 68-01-2915

Traffic safety demonstration program modeling system. Volume II: system manual. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Extent-of-exposure survey of methyl chloride /

Mode of access: Internet.

Industrial hygiene surveys of occupational exposure to mineral wool /

Mode of access: Internet.