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. 2004 May;86(5):3112–3120. doi: 10.1016/S0006-3495(04)74359-3

FIGURE 2.

FIGURE 2

Flash-induced proton transfer reaction of the wild-type (A and C) and Arg-72ppR mutant (B and D). R72Q was used in B and R72A was used in D. A and B show the proton transfer data measured by SnO2 electrode. The potential difference between a pair of SnO2 electrodes was measured using a 15-Hz low-cut filter, which gave the differentiated signals. For the wild-type (A), the light pulse (4-ms duration) led first to proton release, followed by the uptake. B shows the opposite sequence for R72QppR. The magnitudes of the first photoresponses are plotted against pH in C and D for the wild-type and R72AppR. The medium for all experiments was 400 mM NaCl. The pH values in A and B were 5.0 and 8.0, respectively. For detailed experimental procedures, see Materials and Methods.