Spectroscopic discrimination of the three rhodopsinlike pigments in Halobacterium halobium membranes.
Spectroscopic discrimination of the three rhodopsinlike pigments in Halobacterium halobium membranes.
复制标题
盐杆菌膜中三种视紫红质色素的光谱辨别。
DOI：
10.1016/s0006-3495(83)84345-8
复制
发表时间：
1983
影响因子：
3.4
通讯作者：
Bogomolni,RA
中科院分区：
文献类型：
--
作者：
Spudich,JL;Bogomolni,RA
盐生盐杆菌的膜除了含有质子泵细菌视紫红质外，还含有两种具有光化学活性的视网膜色素。一种是卤视紫红质，也是一种具有快速(毫秒级)光反应周期的生电离子泵。另一种是S-视紫红质，在相同的光谱区域活跃，但光反应周期要慢得多(在几秒钟的尺度上)。S-视紫红质不是一个生电离子泵，它的性质表明它是趋光性的受体色素。这三种颜料的吸收光谱都非常相似。最近分离的缺乏细菌视紫红质和卤视紫质以及视网膜合成的突变体使我们能够解析S视紫红质和卤视紫质的吸收光谱。在中性pH条件下，S-视紫红质的最大吸收波长为587+/-2 nm，卤视紫红质的最大吸收波长为578+/-2 nm。在pH 10.8时，S-视紫红质的最大吸收波长移动到552 nm，消光系数略有下降(15%)，而卤视紫红质在500 nm以上完全消光。这两种效应都是完全可逆的，可以测定S-视紫红质和卤视紫红质在含有这两种色素的膜剂中的含量。这两种色素都出现在对盐生梭菌膜的早期研究中，鉴于这些发现，必须重新解释几个观察结果。
Membranes of Halobacterium halobium contain two photochemically reactive retinal pigments in addition to the proton pump bacteriorhodopsin. One, halorhodopsin, is also an electrogenic ion pump with a fast (on a scale of milliseconds) photoreaction cycle. The other, s-rhodopsin, is active in the same spectral region, but has a much slower photoreaction cycle (on a scale of seconds). S-rhodopsin is not an electrogenic ion pump and its properties suggest it functions as the receptor pigment for phototaxis. All three pigments have very similar absorption spectra. The recent isolation of mutants deficient in both bacteriorhodopsin and halorhodopsin and in retinal synthesis has allowed us to resolve the absorption spectra of s-rhodopsin and halorhodopsin. At neutral pH s-rhodopsin has an absorption maximum at 587 +/- 2 nm and halorhodopsin at 578 +/- 2 nm. At pH 10.8, lambda max for s-rhodopsin is shifted to 552 nm and extinction decreases slightly (15%) while halorhodopsin loses all extinction above 500 nm. Both effects are fully reversible and allow determination of the amounts of s-rhodopsin and halorhodopsin in membrane preparations containing both pigments. Both pigments were present in earlier studies of H. halobium membranes, and in view of these findings, several observations must be reinterpreted.