Identification of the Cl(-)-binding site in the human red and green color vision pigments.
Identification of the Cl(-)-binding site in the human red and green color vision pigments.
复制标题
人类红色和绿色视觉色素中 Cl(-)-结合位点的鉴定。
DOI：
10.1021/bi00060a001
复制
发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Oprian,DD
中科院分区：
文献类型：
--
作者：
Wang,Z;Asenjo,AB;Oprian,DD
1993年1月19日收到的修订手稿摘要：已知氯离子可以结合和改变某些但不是所有视觉色素的吸收光谱。本文报道了人的红色和绿色视觉色素与氯离子结合并使其最大吸收峰发生较大红移，这些色素中18种不同正电荷氨基酸的突变确定了氯离子结合部位的两个残基：His197和Lys200。His197和Lys200在所有长波长锥体色素中都是严格保守的，但在所有视紫红质和短波长锥体色素中都不存在。这一事实表明，当祖先的色素获得与氯结合的能力时，长波长色素的进化分支就建立了，结果是将吸收最大值向更长的波长移动。已知许多但不是所有视觉色素的光谱性质受到氯离子与蛋白质上高亲和力位点结合的显著影响。这一效应首先由Cresitelli(1977)对壁虎的色素进行了观察。壁虎有两种视觉色素，一种是蓝色(最大为467 nm)，另一种是绿色(最大为521 nm)。蓝色颜料的光谱性质与氯化物无关。然而，在氯离子耗尽的介质中，绿色素的最大吸收波长发生了10-15 nm的蓝移。同样，从鸡肉中提取的红色色素碘多酚对氯离子表现出敏感性(Knowles，1976)。在氯化物存在下，碘化钠在562 nm处有最大吸收。除去氯化物后，最大值发生蓝移，约为520 nm。氯离子与碘视蛋白结合的解离常数(K<；j)约为1 mm(Fager&Fager，1979；Shichida等，
Revised Manuscript Received January 19, 1993 abstract: Chloride ions are known to bind and alter the absorption spectra of some but not all visual pigments. In this report, the human red and green color vision pigments are shown to bind Cl" andto undergo a large red shift intheir absorption maxima. Mutation of 18 different positively charged amino acids in these pigments identified two residues, His197 and Lys200, in the Cl"-binding site. His197 and Lys200 are strictly conserved in all long-wavelength cone pigments but are absent in all rhodopsins and shortwavelength cone pigments. This fact suggests that the evolutionary branch of the long-wavelength pigments was established when an ancestral pigment acquired the ability to bind Cl" and, as a result, shift the absorption maximum to longer wavelengths.The spectral properties of many, but not all, visual pigments are known to be influenced significantly by the binding of chloride ions to high-affinity sites on the proteins. This effect was first observed byCrescitelli (1977) for pigments of the Tokay gecko (Gecko gecko). G. gecko have two visual pigments, one blue (467-nm maximum) and one green (521-nm maximum). The spectral properties of the blue pigment are independent of chloride. However, the green pigment absorption maximum undergoes a 10-15-nm blue shift in chloride-depleted medium. Similarly, iodopsin, the red pigment from chicken, displays a sensitivity to chloride ion (Knowles, 1976). In the presence of chloride, iodopsin absorbs maximally at 562 nm. Upon removal of chloride, the maximum undergoes a blue shift to about 520 nm. The dissociation constant (K< j) for binding of chlorideto iodopsin is about 1 mM (Fager & Fager, 1979; Shichida et al.,