Studies in rhodopsin. 4. Preparation of rhodopsin

Abstract

The history of visual pigments has been reviewed on numerous occasions-see Collins & Morton (1950) and In recent years the methods used in preparing solutions of rhodopsin have involved at least partial separation of rod outer segments. If retinas are shaken vigorously in saline or other suitable suspending medium the rod outer segments become detached. Various methods have been used for separating these 'rods' from the remainder of the retinal suspension. Lythgoe (1937) poured the suspension through fine wire gauze and showed that the rods, pigment granules and a few isolated cells passed through, but that the main mass of nuclear and fibrous material was held back. Krause & Sidwell (1938) centrifuged the retinal suspension and found that the rods formed a layer on top of the other retinal fragments which could then be scraped off. Saito (1938) used 40-45 g. sucrose/100 ml. water as the suspending medium and found that on centrifuging, the rods remained in suspension. The rods could be thrown down when diluted with sufficient saline. The method has been used by In addition, Wald (1949) has often simply scraped the rods off the retina with a fine spatula or forceps.