STRUCTURE AND FUNCTION OF RETINOCHROME

Retinochrome is a photo-isomerase of all-trans-retinal to the Il-cis-i somer for rhodopsin synthesis. This protein is probably folded into se ven alpha-helices spanning the membranes. Upon irradiation, it is conv erted to metaretinochrome, via pre-lumi- and lumiretinochrome, which a re stable under 50 and 250 K, respectively. A series of analogue studi es revealed that the cyclohexene ring and 6-s-cis-twisted conformation are important for binding. Modification of the 14-position suggests c lose location of the 14-H to the counterion.