McRee D E, Meyer T E, Cusanovich M A, Parge H E, Getzoff E D
J Biol Chem. 1986 Oct 15;261(29):13850-1.
A photoactive yellow protein purified from the phototrophic bacterium Ectothiorhodospira halophila, has been crystallized by vapor diffusion from ammonium sulfate solution. The hexagonal crystals are in space group P6(3) with unit cell dimensions a = b = 66.89, c = 40.68 A and appear to have one 15,000-dalton protein in the asymmetric unit. Photoactive yellow protein contains a chromophore with retinal-like properties; its color can be reversibly bleached, by visible light, with kinetics similar to those of sensory rhodopsin. The crystals can also be bleached by an intense visible light source without cracking, but are not bleached by x-rays. This suggests that structures can be obtained for both bleached and colored conformations of the protein-bound chromophore. The crystals diffract strongly to at least 1.3 A resolution, are resistant to radiation damage, and are suitable for a high resolution structure determination. The covalently bound chromophore and photobleaching characteristics of the protein offer unique opportunities to study protein conformational change and refolding as well as to understand the mechanisms of light-induced conformational change at atomic resolution.
从嗜盐外硫红螺菌（Ectothiorhodospira halophila）中纯化得到的一种光活性黄色蛋白，已通过硫酸铵溶液的气相扩散法结晶。六边形晶体属于空间群P6(3)，晶胞参数a = b = 66.89，c = 40.68 Å，不对称单元中似乎含有一个15,000道尔顿的蛋白质。光活性黄色蛋白含有一种具有类视黄醛性质的发色团；其颜色可被可见光可逆漂白，动力学过程与感官视紫红质相似。晶体也可被强可见光源漂白而不破裂，但不会被X射线漂白。这表明可以获得蛋白质结合发色团的漂白态和有色态的结构。这些晶体在至少1.3 Å分辨率下有强烈衍射，抗辐射损伤，适合进行高分辨率结构测定。该蛋白的共价结合发色团和光漂白特性为研究蛋白质构象变化和重折叠提供了独特机会，也有助于在原子分辨率下理解光诱导构象变化的机制。
