title: Bleaching of bacteriorhodopsin by continuous light.
abstract: A new two step photobleaching process is observed under continuous illumination of bacteriorhodopsin. This photobleaching is considerable even at physiological temperatures and becomes large at 50-60 degrees C. The photobleaching also increases with increasing pH from 7 to 10. We suggest that the bleaching at its final stage could be due to the dissociation of the retinal and a local thermal denaturation-like process. These facts may question the generally held belief that BR is a stable protein in vivo for a long period of time. Our results may have relevance also to practical applications of bacteriorhodopsin where the stability of bacteriorhodopsin is a key issue. In certain instances, the use of bacteriorhodopsin may require cooled conditions. Here, we defined the conditions under which bacteriorhodopsin is stable. The permanent photobleaching offers a new way of picture imaging and information input for bacteriorhodopsin-based optical devices.
authors.affiliation: Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Szeged.
authors.forename: Z
authors.initials: Z
authors.lastname: Dancsházy
authors.forename: Z
authors.initials: Z
authors.lastname: Tokaji
authors.forename: A
authors.initials: A
authors.lastname: Dér
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D016247:Information Storage and Retrieval; D008027:Light; D055096:Optical Devices; D010777:Photochemistry; D017785:Photons; D011489:Protein Denaturation; D018717:Purple Membrane / Q000737:chemistry; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D001436:Bacteriorhodopsins