鸡视碘质的结构与光漂白过程

Structure and photobleaching process of chicken iodopsin.

作者信息

Yoshizawa T, Imamoto Y

机构信息

Department of Information Systems Engineering, Faculty of Engineering, Osaka Sangyo University, Japan.

出版信息

Biophys Chem. 1995 Sep-Oct;56(1-2):57-62. doi: 10.1016/0301-4622(95)00015-p.

DOI:10.1016/0301-4622(95)00015-p

PMID:7662869

Abstract

Iodopsin, a dominant cone pigment in a chicken retina, has an absorption spectrum in longer wavelength region than rhodopsin. To account for this red-shift of iodopsin, we had proposed a structural model from retinal analogue experiments, in which iodopsin would have a relatively long distance between the protonated Schiff base nitrogen and the counterion. This was confirmed by a resonance Raman spectroscopy. The photochemical properties of iodopsin were studied and compared with those of rhodopsin, which revealed the following differences. The regeneration rate of iodopsin with 11-cis-retinal was 240 times faster than rhodopsin. Meta-iodopsin II, the signalling state of iodopsin, decayed about 100 times faster than meta-rhodopsin II. The Km value of meta-iodopsin II and rhodopsin kinase was lower than meta-rhodopsin II. These results are in consistent with rapid adaptation and low photosensitivity of cones relative to those of rods.

摘要

视锥蛋白是鸡视网膜中的主要视锥色素，其吸收光谱位于比视紫红质更长的波长区域。为了解释视锥蛋白的这种红移现象，我们通过视网膜类似物实验提出了一种结构模型，其中视锥蛋白的质子化席夫碱氮与抗衡离子之间的距离相对较长。这一点通过共振拉曼光谱得到了证实。对视锥蛋白的光化学性质进行了研究，并与视紫红质的光化学性质进行了比较，结果显示出以下差异。视锥蛋白与11-顺式视黄醛的再生速率比视紫红质快240倍。视锥蛋白的信号转导状态间视锥蛋白II的衰变速度比间视紫红质II快约100倍。间视锥蛋白II与视紫红质激酶的Km值低于间视紫红质II。这些结果与视锥细胞相对于视杆细胞的快速适应性和低光敏性相一致。