CAROTENOIDS AND THE VISUAL CYCLE.
CAROTENOIDS AND THE VISUAL CYCLE.
复制标题
DOI：
10.1085/jgp.19.2.351
复制
发表时间：
1935-11-20
期刊：
影响因子：
--
通讯作者：
Wald G
中科院分区：
文献类型：
--
作者：
Wald G
1.类胡萝卜素已被确定，并在几种青蛙的眼睛测量其数量。本文报道了一只R. pipiens或esculenta eye含有约1γ的叶黄素和约4γ的维生素A。在光适应期间，叶黄素含量下降福尔斯10%至20%。光适应视网膜仅含有约0.2-0.3 γ的维生素A。3.暗适应视网膜只含有微量的维生素A。用氯仿破坏它们视觉上的紫色，释放出一种迄今为止尚未描述的类胡萝卜素，视黄烯。视紫红色被光漂白成视黄色也释放出视黄烯。游离的视黄烯通过两个热过程从离体视网膜中除去：恢复为可见紫色和分解为无色产物，包括维生素A。这是光适应视网膜的维生素A的来源。4.已经漂白并完全褪色的孤立视网膜含有的维生素A是来自光适应动物的视网膜的数倍。因此，视觉紫色系统消耗维生素A，并依赖于饮食来替代它。5.视紫红表现为一种共轭蛋白质，其中视黄烯是辅基。6.维生素A是视觉紫色的前体，也是其分解的产物。因此，视觉过程构成了一个循环。
1. Carotenoids have been identified and their quantities measured in the eyes of several frog species. The combined pigment epithelium and choroid layer of an R. pipiens or esculenta eye contain about 1γ of xanthophyll and about 4γ of vitamin A. During light adaptation the xanthophyll content falls 10 to 20 per cent. 2. Light adapted retinas contain about 0.2–0.3 γ of vitamin A alone. 3. Dark adapted retinas contain only a trace of vitamin A. The destruction of their visual purple with chloroform liberates a hitherto undescribed carotenoid, retinene. The bleaching of visual purple to visual yellow by light also liberates retinene. Free retinene is removed from the isolated retina by two thermal processes: reversion to visual purple and decomposition to colorless products, including vitamin A. This is the source of the vitamin A of the light adapted retina. 4. Isolated retinas which have been bleached and allowed to fade completely contain several times as much vitamin A as retinas from light adapted animals. The visual purple system therefore expends vitamin A and is dependent upon the diet for its replacement. 5. Visual purple behaves as a conjugated protein in which retinene is the prosthetic group. 6. Vitamin A is the precursor of visual purple as well as the product of its decomposition. The visual processes therefore constitute a cycle.