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首页> 外文期刊>Biochemistry >Photochemistry of the primary event in short-wavelength visual opsins at low temperature.
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Photochemistry of the primary event in short-wavelength visual opsins at low temperature.

机译：短波长视觉视蛋白在低温下主要事件的光化学反应。

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Two short-wavelength cone opsins, frog (Xenopus laevis) violet and mouse UV, were expressed in mammalian COS1 cells, purified in delipidated form, and studied using cryogenic UV-vis spectrophotometry. At room temperature, the X. laevis violet opsin has an absorption maximum at 426 nm when generated with 11-cis-retinal and an absorption maximum of 415 nm when generated with 9-cis-retinal. The frog short-wavelength opsin has two different batho intermediates, one stable at 30 K (lambda(max) approximately 446 nm) and the other at 70 K (lambda(max) approximately 475 nm). Chloride ions do not affect the absorption maximum of the violet opsin. At room temperature, mouse UV opsin has an absorption maximum of 357 nm, while at 70 K, the pigment exhibits a bathochromic shift to 403 nm with distinct vibronic structure and a strong secondary vibronic band at 380 nm. We have observed linear relationships when analyzing the energy difference between the initial and bathochromic intermediates and the normalized difference spectra of the batho-shifted intermediates of rod and cone opsins. We conclude that the binding sites of these pigments change from red to green to violet via systematic shifts in the position of the primary counterion relative to the protonated Schiff base. The mouse UV cone opsin does not fit this trend, and we conclude that wavelength selection in this pigment must operate via a different molecular mechanism. We discuss the possibility that the mouse UV chromophore is initially unprotonated.
机译：在哺乳动物COS1细胞中表达了两种短波锥视蛋白，即青蛙（Xenopus laevis）紫和小鼠UV，并以脂质形式纯化，并使用低温UV-vis分光光度法进行了研究。在室温下，X.laevis紫色视蛋白在11-顺式视网膜产生时的最大吸收为426 nm，在9-顺式视网膜产生时的最大吸收为415nm。青蛙短波视蛋白具有两种不同的深碱性中间体，一种稳定在30 K（λ（最大）约为446 nm），另一种稳定在70 K（λ（最大）约为475 nm）。氯离子不会影响紫色视蛋白的最大吸收量。在室温下，小鼠紫外线视蛋白的最大吸收值为357 nm，而在70 K时，该颜料表现出向红移至403 nm的红移现象，具有明显的振动电子结构和在380 nm处具有很强的次级振动电子带。当分析初始和红变中间体之间的能量差以及棒视蛋白和视锥蛋白的红移中间体的归一化差异光谱时，我们已经观察到线性关系。我们得出结论，这些颜料的结合位点通过相对于质子化席夫碱的主要抗衡离子位置的系统移位而从红色变为绿色，变为紫色。小鼠紫外线锥视蛋白不符合这种趋势，因此我们得出结论，这种颜料的波长选择必须通过不同的分子机制进行。我们讨论了鼠标紫外线生色团最初未质子化的可能性。

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