Studies in rhodopsin. 5. Chemical analysis of retinal material

Abstract

The following values were obtained for cattle whole retinas, cattle rod outer segments, and frog whole retinas in mg./l00 g. fresh tissue: rhodopsin 5.5, 22.6, 1.35; acid-soluble P 61.2, 33.5, 48.0; phospholipin P 92.5, 320.0, 87.8; desoxypentosenucleic acid (DNA) P 59.7, 0.8, 63.5; pentosenucleic acid P 20.9, 17.5, 27.1; and phospho-protein P 5.5, 9.1, 7.2. Rod outer segments contain little DNA and about 30% phospholipin on dry weight. After fragmentation in a homogenizer, cattle rod outer segments gave form fractions on differential centrifugation. In terms of Sjostrand''s electron microscope analysis of rods, the middle fractions comprise the disks in the outer segments, contain over 30% phospholipin and practically all their P is in this form.