Hara-Nishimura I, Kondo M, Nishimura M, Hara R, Hara T
Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan.
FEBS Lett. 1993 Nov 29;335(1):94-8. doi: 10.1016/0014-5793(93)80447-3.
Squid (Todarodes pacificus) retinochrome was reduced to N-retinyl protein with borane dimethylamine and cleaved by CNBr. The retinyl peptide was then isolated by chromatography while being monitored for absorbances at 215 and 330 nm, and the N-terminal amino acid sequence was determined to be Ser-Lys-Thr-Gly-X-Ala-Leu-Phe-Pro. This sequence was the same that we had observed at the 7th transmembrane domain of retinochrome whose structure was reported previously. During Edman degradation of the retinyl peptide, the yield of the PTH-lysine at the second cycle was lower than those of the other PTH-amino acids, proving that the lysine residue forms a Schiff's base with retinal (Lys-275 in retinochrome). The amino acid sequence surrounding the retinal-binding lysine in retinochrome greatly differed from those in a variety of known visual pigments. This fact would be associated with the difference in the photoisomerization of chromophore between retinochrome and rhodopsin. The protein structure of retinochrome is also compared with that of rhodopsin in Todarodes.
用硼烷二甲胺将太平洋褶柔鱼（Todarodes pacificus）视紫红质还原为N - 视黄醛蛋白，并用溴化氰裂解。然后通过色谱法分离视黄醛肽，同时监测其在215和330 nm处的吸光度，并确定其N端氨基酸序列为Ser - Lys - Thr - Gly - X - Ala - Leu - Phe - Pro。该序列与我们之前报道的视紫红质结构中第7个跨膜结构域所观察到的序列相同。在视黄醛肽的埃德曼降解过程中，第二个循环中PTH - 赖氨酸的产率低于其他PTH - 氨基酸，证明赖氨酸残基与视黄醛形成席夫碱（视紫红质中的Lys - 275）。视紫红质中围绕视黄醛结合赖氨酸的氨基酸序列与多种已知视觉色素中的序列有很大差异。这一事实可能与视紫红质和视紫质中发色团的光异构化差异有关。还将视紫红质的蛋白质结构与太平洋褶柔鱼中的视紫质结构进行了比较。
