Accessibility of the iodopsin chromophore.
Iodopsin can replace its chromophore (11-cis retinal) by added 9-cis retinal, resulting in the formation of isoiodopsin. NaBH4 bleaches iodopsin in the dark. In a relatively low concentration of digitonin, the scotopsin (the protein moiety of chicken rhodopsin) removes 11-cis retinal from iodopsin in the dark. These facts suggest that the linkage of the chromophore to opsin in the iodopsin molecule (presumably a Schiff-base linkage) is accessible to these reagents, which is different from the situation in rhodopsin.
D000429:Alcohol Oxidoreductases; D000818:Animals; D001665:Binding Sites; D001894:Borohydrides; D002645:Chickens; D003624:Darkness; D005136:Eye Proteins; D007467:Iodoproteins; D008055:Lipids; D010084:Oxidation-Reduction; D010088:Oxidoreductases; D012168:Retinal Pigments; D012172:Retinaldehyde; D012243:Rhodopsin; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet
D001894:Borohydrides; D005136:Eye Proteins; D007467:Iodoproteins; D008055:Lipids; D012168:Retinal Pigments; C011348:scotopsin; D012243:Rhodopsin; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; D012172:Retinaldehyde