Effects of modified chromophores on the spectral sensitivity of salamander, squirrel and macaque cones.
Effects of modified chromophores on the spectral sensitivity of salamander, squirrel and macaque cones.
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修饰发色团对蝾螈、松鼠和猕猴锥体光谱敏感性的影响。
DOI：
10.1113/jphysiol.1990.sp018082
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Baylor,DA
中科院分区：
文献类型：
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作者：
Makino,CL;Kraft,TW;Mathies,RA;Lugtenburg,J;Miley,ME;vanderSteen,R;Baylor,DA
1. 化学修饰的视网膜发色团用于研究产生锥体色素特征光谱吸收的机制。用电记录法测定了蝾螈、松鼠和猕猴视网膜单视锥细胞的光谱灵敏度。然后用漂白色素取代发色团，并用视网膜类似物再生。2. 将漂白后的锥体暴露在9 -顺式视网膜下一段时间（少于20分钟），其闪光灵敏度恢复到漂白前值的0.2左右。同样暴露于锁定的6 - s - cis， 9 - cis类似物中，可使漂白前的值恢复约0.03。3. 与闪光灵敏度不同，饱和光电流幅值在漂白和再生色素后往往完全恢复。4. 当蝾螈长波长敏感（红色）锥体中的3 -脱氢视网膜发色团被11 -顺式视网膜取代时，发色团中的共轭链缩短，光谱灵敏度发生了67 nm的蓝移。含有平面锁定6 - s - cis的颜料。9 -顺式视网膜类似物的吸收波长比含有未修饰的9 -顺式视网膜的吸收波长长得多。视蛋白位移（一种衡量蛋白质改变发色团吸收能力的指标）在锁定的类似物中比在9 -顺式视网膜中更大。这表明天然发色团在这些色素中呈现扭曲的6‐s‐cis构象。6. 红色和绿色猕猴视锥细胞含有9 -顺式视网膜或平面锁定6 -顺式视网膜的光谱灵敏度。9 -顺式视网膜保留了天然色素30 nm的分离特性。这表明视网膜发色团对6 - 7碳键的吸收不同。
1. Chemically modified retinal chromophores were used to investigate the mechanisms that produce the characteristic spectral absorptions of cone pigments. Spectral sensitivities of single cones from the salamander, squirrel and macaque retina were determined by electrical recording. The chromophore was then replaced by bleaching the pigment and regenerating it with a retinal analogue. 2. Exposing a bleached cone to 9‐cis‐retinal for a brief period (less than 20 min) caused its flash sensitivity to recover to about 0.2 of the pre‐bleach value. Similar exposure to a locked 6‐s‐cis, 9‐cis analogue gave a recovery to about 0.03 of the pre‐bleach value. 3. Unlike the flash sensitivity, the saturating photocurrent amplitude often recovered completely after bleaching and regenerating the pigment. 4. When the 3‐dehydroretinal chromophore in the salamander long‐wavelength‐sensitive (red) cone was replaced with 11‐cis‐retinal, shortening the conjugated chain in the chromophore, the spectral sensitivity underwent a blue shift of 67 nm. 5. Pigments containing the planar‐locked 6‐s‐cis.9‐cis‐retinal analogue absorbed at substantially longer wavelength than those containing unmodified 9‐cis‐retinal. The opsin shift, a measure of the protein's ability to modify the chromophore's absorption was larger for the locked analogue than for 9‐cis‐retinal. This suggests that the native chromophore assumes a twisted 6‐s‐cis conformation in these pigments. 6. The spectral sensitivities of red and green macaque cones containing 9‐cis‐retinal or planar‐locked 6‐s‐cis.9‐cis‐retinal retained the 30 nm separation characteristic of the native pigments. This suggests that the different absorptions of of the 6‐7 carbon bond in the retinal chromophore.