The role of the phospholipin in visual purple solutions

Abstract

Solns. of visual purple from frog contain phospholipin from the retina. The wt. of the lipin is not much less than that of the visual purple protein. The lipin absorbs short-wave light and therefore decreases the apparent quantum yield of the photodecom-position of visual purple in solution by blue, etc., light. For the same reason the lipin in the living retina reduces the sensitivity of the eye to short-wave light. The extinction coefficient of the retina lipin is of the same order as that of egg lecithin, and much smaller than those of the caro-tenoids. The lipin is connected with visual purple by a secondary bond possibly similar to that between euglobulin and lecithin. The difficulty to extract the lipin from the solns. and their clarity are due to this bond. An efficient method to free the solns. from phospholipin is electrodialy-sis.