Absolute quantum yields and proof of proton and nonproton transient release and uptake in photoexcited bacteriorhodopsin.
Absolute quantum yields and proof of proton and nonproton transient release and uptake in photoexcited bacteriorhodopsin.
复制标题
绝对量子产率以及光激发细菌视紫红质中质子和非质子瞬时释放和摄取的证明。
DOI：
10.1073/pnas.80.1.178
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发表时间：
1983
影响因子：
11.1
通讯作者：
Mauzerall,D
中科院分区：
文献类型：
--
作者：
Marinetti,T;Mauzerall,D
使用一个敏感的差分交流电导装置，我们已经测量了瞬态离子运动和细菌视紫红质悬浮液的加热后，闪光。来自加热的信号用作吸收光子的内部校准，因此该方法从单次测量中给出绝对量子产率（phi）。在pH 4时，H+吸收先于释放，phi = 0.4。通过改变缓冲液组成，我们可以证明该信号是由于质子。然而，在pH值为8时，瞬时电导增加几乎是独立的缓冲液组合物，表明除H+以外的离子首先被释放，然后被紫膜吸收。如果这些离子是典型的一价阳离子，例如Na+（λ = 50 ohm-1 × cm 2 × equiv-1），则该方法在高盐浓度下具有2或更高的量子产率。
Using a sensitive differential ac conductance apparatus, we have measured transient ion movements in and the heating of bacteriorhodopsin suspensions after a light flash. The signal from the heating serves as an internal calibration of the absorbed photons and therefore the method gives the absolute quantum yield (phi) from a single measurement. At pH 4, H+ uptake precedes release, with phi = 0.4. By varying the buffer composition, we can prove that this signal is due to protons. At pH 8, however, the transient conductance increase is virtually independent of the buffer composition, showing that ions other than H+ are first released and then taken up by the purple membrane. If these ions are typical monovalent cations such as Na+ (lambda = 50 ohm-1 X cm2 X equiv-1), this process has a quantum yield of 2 or more at high salt concentrations.