ETHANOLAMINE ATTACK OF THE BOVINE RHODOPSIN CHROMOPHORE

Ethanolamine attacks the rhodopsin chromophore, bleaching the visual pigment in the dark. Rhodopsin breakdown is first order under all conditions and the kinetic constants of breakdow are linear in ethanolamine concentration, suggesting that it is a specific attack on the retinal binding site, rather than a non-specific denaturation of the molecule. The rate of breakdown accelerated markedly at basic pH's in the range of the pK's of the protein's basic amino acids, implying that charge repulsion distorts the rhodopsin molecule, making ethanolamine penetration easier. © 1979.