Weesie R J, Askin D, Jansen F J, de Groot H J, Lugtenburg J, Britton G
Department of Biochemistry, University of Liverpool, UK.
FEBS Lett. 1995 Mar 27;362(1):34-8. doi: 10.1016/0014-5793(95)00191-b.
MAS (magic angle spinning) 13C NMR has been used to study protein-chromophore interactions in alpha-crustacyanin, the blue astaxanthin-binding carotenoprotein of the lobster, Homarus gammarus, reconstituted with astaxanthins labelled with 13C at the 14,14' or 15,15' positions. Two signals are seen for alpha-crustacyanin containing [14,14'-13C2]astaxanthin, shifted 6.9 and 4.0 ppm downfield from the 134.1 ppm signal of uncomplexed astaxanthin in the solid state. With alpha-crustacyanin containing [15,15'-13C2]astaxanthin, one essentially unshifted broad signal is seen. Hence binding to the protein causes a decrease in electronic charge density, providing the first experimental evidence that a charge redistribution mechanism contributes to the bathochromic shift of the astaxanthin in alpha-crustacyanin, in agreement with inferences based on resonance Raman data [Salares, et al. (1979) Biochim. Biophys. Acta 576, 176-191]. The splitting of the 14 and 14' signals provides evidence for asymmetric binding of each astaxanthin molecule by the protein.
魔角旋转（MAS）13C核磁共振已被用于研究α-甲壳蓝蛋白中的蛋白质-发色团相互作用。α-甲壳蓝蛋白是龙虾（螯龙虾）的蓝色虾青素结合类胡萝卜素蛋白，用在14、14'或15、15'位置标记有13C的虾青素进行了重构。对于含有[14,14'-13C2]虾青素的α-甲壳蓝蛋白，观察到两个信号，相对于固态下未络合虾青素134.1 ppm的信号，向低场位移了6.9 ppm和4.0 ppm。对于含有[15,15'-13C2]虾青素的α-甲壳蓝蛋白，观察到一个基本未位移的宽信号。因此，与蛋白质的结合导致电子电荷密度降低，这提供了第一个实验证据，即电荷重新分布机制促成了α-甲壳蓝蛋白中虾青素的红移，这与基于共振拉曼数据得出的推断一致[Salares等人（1979年），《生物化学与生物物理学报》576, 176 - 191]。14和14'信号的分裂为蛋白质对每个虾青素分子进行不对称结合提供了证据。
