Opsin shift in an aldolase antibody

An antibody-retinal assembly that mimics the opsin shift (OS) of the naturally occurring visual pigments is reported. Both experiments and calculations show that the aldolase antibody 33F12 covalently binds all-trans retinal via a protonated Schiff base with a lysine residue. This chromophore, which exhibits a remarkable opsin red shift (140 nm), represents a useful model system for studying the factors that contribute to the OS.