Effect of lipid surface charges on the purple-to-blue transition of bacteriorhodopsin.
Effect of lipid surface charges on the purple-to-blue transition of bacteriorhodopsin.
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脂质表面电荷对细菌视紫红质从紫色到蓝色转变的影响。
DOI：
10.1073/pnas.84.11.3681
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发表时间：
1987
影响因子：
11.1
通讯作者：
Stoeckenius,W
中科院分区：
文献类型：
--
作者：
Szundi,I;Stoeckenius,W
通过酸滴定或去离子可以将紫色膜（λ max = 568 nm）转化为蓝色膜（λ max = 605 nm）。部分脱脂的紫色膜仅含有初始脂质磷的25%，可以通过酸滴定转变成蓝色形式，但不能通过去离子转变成蓝色形式。脱脂膜的这种可逆转变不需要其他阳离子的存在，并且类似条件下天然膜中颜色变化的pK从3.0到4.0之间转变为1.4。我们得出的结论是，紫色到蓝色的转变仅由质子浓度控制，并且在天然膜中，阳离子仅通过提高脂质酸性基团产生的低表面 pH 值来发挥作用。从去离子天然膜中提取脂质将其颜色从蓝色转变为紫色的观察结果进一步证实了这一结论。膜的两种状态可能反映了细菌视紫红质的两种优选构象，它们由膜表面的质子化变化控制，并且发色团周围电荷的空间分布略有不同。
Purple membrane (lambda max = 568 nm) can be converted to blue membrane (lambda max = 605 nm) by either acid titration or deionization. Partially delipidated purple membrane, containing only 25% of the initial lipid phosphorus, could be converted to a blue form by acid titration but not by deionization. This reversible transition of delipidated membrane did not require the presence of other cations, and the pK of the color change that in native membrane under similar conditions is between 3.0 and 4.0 was shifted to 1.4. We conclude that the purple-to-blue transition is controlled by proton concentration only and that, in native membranes, the cations act only by raising the low surface pH generated by the acidic groups of the lipids. The observation that extraction of lipids from deionized native membrane converts its color from blue to purple further confirms this conclusion. The two states of the membrane probably reflect two preferred conformations of bacteriorhodopsin, which are controlled by protonation changes at the surface of the membrane and differ slightly in the spatial distribution of charges around the chromophore.