DARK-ADAPTED BACTERIORHODOPSIN CONTAINS 13-CIS,15-SYN AND ALL-TRANS,15-ANTI RETINAL SCHIFF-BASES
DARK-ADAPTED BACTERIORHODOPSIN CONTAINS 13-CIS,15-SYN AND ALL-TRANS,15-ANTI RETINAL SCHIFF-BASES
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DOI：
10.1073/pnas.81.6.1706
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
GRIFFIN, RG
中科院分区：
文献类型：
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作者：
HARBISON, GS;SMITH, SO;GRIFFIN, RG
冻干的暗适应[14- 13 C]视黄酰标记的细菌视紫红质[Halobacterium halobium]的13 C NMR光谱显示，相对于全反式异构体和模型化合物，分配给13-顺式异构体的13 C-14共振的大的异常高场位移。这归因于γ。这是由C-14视网膜质子和ε上的质子之间的空间相互作用引起的。赖氨酸的CH 2。因此，暗适应细菌视紫红质显然由全反式、15-反式（反式或E）和13-顺式、15-顺式（顺式或Z）异构体的混合物组成。这些发生在. apprx中。4：6的比例，通常被鉴定为bR 568和bR 548。这一结论是基于对各向同性和各向异性化学位移的检查以及与质子化酮亚胺中C = N键相邻的C的13 C位移的比较。其他可能的起源的异常位移进行检查，并显示是不足以占的位移或位移张量的性质的大小。这一发现的结构和光化学的细菌视紫红质的后果进行了讨论。
13C NMR spectra of lyophilized dark-adapted [14-13C]retinyl-labeled bacteriorhodopsin [Halobacterium halobium] show a large anomalous upfield shift for the 13C-14 resonance assigned to the 13-cis isomer, relative to the all-trans isomer and model compounds. This is attributed to the .gamma. effect, which results from a steric interaction between the C-14 retinal proton and the protons on the .epsilon. CH2 of the lysine. Dark-adapted bacteriorhodopsin is thus apparently composed of a mixture of all-trans,15-anti (trans or E) and 13-cis,15-syn (cis or Z) isomers. These occur in an .apprx. 4:6 ratio and are commonly identified as bR568 and bR548. This conclusion is based on an examination of the isotropic and anisotropic chemical shifts and a comparison with 13C shifts of the C adjacent to the C.dbd.N linkage in protonated ketimines. Other possible origins for the anomalous shift are examined and shown to be insufficient to account for the size of the shift or the nature of the shift tensor. The consequences of this finding for the structure and photochemistry of bacteriorhodopsin are discussed.