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Invertebrate opsins are unique among the visual pigments because the light-activated conformation, metarhodopsin, is stable following exposure to light in vivo. Recovery of the light-activated pigment to the dark conformation (or resting state) occurs either thermally or photochemically. There is no evidence to suggest that the chromophore becomes detached(More)
Retinal photoreceptors are noisy. They generate discrete electrical events in the dark indistinguishable from those evoked by light and thereby limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature-dependent and have been attributed to thermal isomerizations of the vitamin A chromophore of rhodopsin,(More)
The structural changes that accompany activation of a G-protein coupled receptor (GPCR) are not well understood. To better understand the activation of rhodopsin, the GPCR responsible for visual transduction, we report studies on the three-dimensional structure for the activated state of this receptor, metarhodopsin II. Differences between the(More)
Optical control of the primary step of photoisomerization of the retinal molecule in bacteriorhodopsin from the all-trans to the 13-cis state was demonstrated under weak field conditions (where only 1 of 300 retinal molecules absorbs a photon during the excitation cycle) that are relevant to understanding biological processes. By modulating the phases and(More)
The current and potential uses of bacteriorhodopsin in optical computing and memory devices are reviewed. The protein has significant potential for use in these applications due to unique intrinsic photophysical properties, and the range of chemical and genetic methods available for optimizing performance for specific application environments. The intrinsic(More)
Retinal photoreceptors generate discrete electrical events in the dark indistinguishable from those evoked by light and the resulting dark signals limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature dependent and in both vertebrate and invertebrate photoreceptors require activation energies usually(More)
The photobleaching pathway of a short-wavelength cone opsin purified in delipidated form (lambda(max) = 425 nm) is reported. The batho intermediate of the violet cone opsin generated at 45 K has an absorption maximum at 450 nm. The batho intermediate thermally decays to the lumi intermediate (lambda(max) = 435 nm) at 200 K. The lumi intermediate decays to(More)
We describe our efforts towards constructing a hybrid protein-silicon neuromorphic photosensor based on the photo-active protein bacteriohodopsin. This protein displays an differential photosensitivity similar to the response of the receptive field of an X-type retinal ganglion cell. Similar bacteriohodopsin photoelectrode arrays display inherent edge(More)
We propose a terahertz (far-infrared) circular dichroism-based life-detection technology that may provide a universal and unequivocal spectroscopic signature of living systems regardless of their genesis. We argue that, irrespective of the specifics of their chemistry, all life forms will employ well-structured, chiral, stereochemically pure macromolecules(More)