CHROMOPHORE OF SENSORY RHODOPSIN-II FROM HALOBACTERIUM-HALOBIUM
CHROMOPHORE OF SENSORY RHODOPSIN-II FROM HALOBACTERIUM-HALOBIUM
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DOI：
10.1021/bi00164a027
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发表时间：
1992-12-15
期刊：
影响因子：
2.9
通讯作者：
ENGELHARD, M
中科院分区：
文献类型：
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作者：
SCHARF, B;HESS, B;ENGELHARD, M
光感受器视紫红质II （sR-II）富集120倍。最终产物sR-II的比含量为3 nmol /mg蛋白质。对富集的光感受器进行了光谱测量。在部分纯化受体的绝对吸收光谱中，可见范围内的主峰对应于sR-II，最大峰在488 nm处。细胞色素仅在415 nm处的一小段光谱中有贡献。羟胺漂白过程中sR-II的消光系数为48 000 M-1 cm-1。还原的发色团显示出明显的精细结构，这是由于视黄醇残基的共平面性。用高效液相色谱法测定了视网膜提取物中富集光感受器的发色团的异构体组成。适应黑暗的sR-II含有80%的全反式和20%的13-顺式视网膜。光照后，这一比例变为1:1，表明sR-II在光循环过程中发生了顺式异构化。
The photoreceptor sensory rhodopsin II (sR-II) was enriched 120-fold from cell membranes of Halobacterium halobium. The final preparation yields sR-II with a specific content of 3 nmol of sR-II/mg of protein. The spectroscopic measurements were performed on the enriched photoreceptor solubilized in digitonin. In the absolute absorption spectrum of the partially purified receptor, the main peak in the visible range corresponded to sR-II with a maximum at 488 nm. Cytochromes contributed to the spectrum only in a minor band at 415 nm. The extinction coefficient of sR-II was estimated from difference spectra during bleaching with hydroxylamine to be 48 000 M-1 cm-1. The reduced chromophore displayed a pronounced fine structure which is due to the coplanarity of the retinyl residue. The isomeric composition of the chromophore from the enriched photoreceptor was determined in retinal extracts in HPLC. The dark-adapted sR-II contains 80% all-trans- and 20% 13-cis-retinal. After illumination, the ratio changed to 1:1, indicating a trans-cis isomerization during the photocycle of sR-II.