Bernstein P S, Law W C, Rando R R
Proc Natl Acad Sci U S A. 1987 Apr;84(7):1849-53. doi: 10.1073/pnas.84.7.1849.
The key biochemical process of the vertebrate visual cycle required for rhodopsin regeneration, 11-cis-retinoid production from all-trans-retinoids, is shown to occur in vitro. A 600 X g supernatant from a frog retina/pigment epithelium homogenate transforms added all-trans-[3H]retinol, in a time-dependent fashion, to a mixture of 11-cis-retinol, 11-cis-retinal, and 11-cis-retinyl palmitate. 13-cis-Retinoids are formed in only minor amounts by nonspecific processes. Studies using washed particulate fractions of the 600 X g supernatant indicate that all-trans-[3H]retinol is isomerized to 11-cis-retinoids much more effectively than is all-trans-[3H]retinal or all-trans-[3H]retinyl palmitate. The 11-cis-retinoid biosynthetic activity is heat-labile, sedimentable by high-speed centrifugation, and largely found in the pigment epithelium rather than in the neural retina.
视紫红质再生所需的脊椎动物视觉循环的关键生化过程，即从全反式视黄醛生成11-顺式视黄醛，已证实在体外可以发生。青蛙视网膜/色素上皮匀浆的600×g上清液能将添加的全反式-[3H]视黄醇以时间依赖性方式转化为11-顺式视黄醇、11-顺式视黄醛和11-顺式视黄醇棕榈酸酯的混合物。13-顺式视黄醛仅通过非特异性过程少量形成。使用600×g上清液的洗涤颗粒部分进行的研究表明，全反式-[3H]视黄醇异构化为11-顺式视黄醛的效率远高于全反式-[3H]视黄醛或全反式-[3H]视黄醇棕榈酸酯。11-顺式视黄醛生物合成活性对热不稳定，可通过高速离心沉淀，并且主要存在于色素上皮中而非神经视网膜中。
