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. 1997 May 13;94(10):5028–5033. doi: 10.1073/pnas.94.10.5028

Figure 2.

Figure 2

The 9,11-bridged retinal acts to rescue the long-lived O intermediate in the Leu-93 → Ala mutant. (A) Transient changes in absorbance of the Leu-93 → Ala mutant (with native retinal) to follow decay of the O intermediate (measured at 625 nm). Note the long time scale for the decay. (B) Same as in A except native retinal was replaced by the 9,11-bridged retinal. Changes in absorbance at 410 nm (M intermediate) and at 625 nm (O intermediate) are shown. (C) Transient changes in absorbance of wild-type bacteriorhodopsin (with native retinal) showing the kinetics of the M (measured at 410 nm) and O (measured at 640 nm) intermediates. (D) Same as in C except native retinal was replaced by the 9,11-bridged retinal. Comparison of the decay of the O intermediate in the different panels shows that the 9,11-bridged retinal acts to accelerate the decay of the O intermediate by ≈550-fold in the Leu-93 → Ala mutant while leaving it nearly unchanged in wild-type bacteriorhodopsin.