Light isomerizes the chromophore of rhodopsin, 11-cis retinal (formerly retinene), to the all-trans configuration. This introduces a succession of unstable intermediates-pre-lumirhodopsin, lumirhodopsin, metarhodopsin -in which all-trans retinal is still attached to the chromophoric site on opsin. Finally, retinal is hydrolyzed from opsin. The present experiments show that metarhodopsin exists ...

Digitonin solutions of labelled rhodopsin, containing (3)H in the retinyl moiety, were prepared by two related methods. Labelled rhodopsin was also prepared for the first time in cetyltrimethylammonium bromide and purified by column chromatography. It was shown that only certain rhodopsin preparations on denaturation in the dark and the reduction with sodium borohydride gave up to 60% of the ra...

Fourier transform infrared difference spectra were measured at 30-s intervals after a complete bleach of rhodopsin (rho) samples at 20 degrees C and three different pH values. At each pH, all of the spectra could be fit globally to two exponential decay processes. Using a branched unimolecular kinetic model in which metarhodopsin II (meta II) is hydrolyzed to opsin and retinal both directly and...

The ability of photoactivated rhodopsin to achieve the enzymatically active metarhodopsin II conformation is exquisitely sensitive to bilayer hydrophobic thickness. The sensitivity of rhodopsin to the lipid matrix has been explained by the hydrophobic matching theory, which predicts that lipid bilayers adjust elastically to the hydrophobic length of transmembrane helices. Here, we examined if b...

background and objectives : halophilic bacteria produce a variety of pigments, which function as immune modulators and have prophylactic action against cancers. in this study, colorful halophilic bacteria were isolated from solar salt lake and their pigments was extracted in optimal environmental conditions and compared with the pigments of halorubrum sodomense atcc 33755. materials and methods...

Detergent-solubilized bovine rhodopsin produces mixed detergent/lipid/protein micelles. The effect of dodecyl maltoside detergent on the thermal stability of dark-state rhodopsin, and upon formation of the different intermediates after rhodopsin photobleaching (metarhodopsin II and metarhodopsin III), and upon transducin activation has been studied. No significant effect is observed for the the...

Metarhodopsin-II is the light-excited form of rhodopsin that triggers G protein function. Metarhodopsin-II is stabilized when the N-terminus of the carboxyl (340-350) tail peptide of the alpha-subunit of transducin (Gtalpha) is crosslinked to rhodopsin cysteine 140 or the 340-350 peptide C-terminus of Gtalpha is crosslinked to rhodopsin cysteine 316. When the N-terminus of the peptide is couple...

A novel fluorescence method has been developed for detecting the light-induced conformational changes of rhodopsin and for monitoring the interaction between photolyzed rhodopsin and G-protein or arrestin. Rhodopsin in native membranes was selectively modified with fluorescent Alexa594-maleimide at the Cys(316) position, with a large excess of the reagent Cys(140) that was also derivatized. Mod...