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. Author manuscript; available in PMC: 2010 Aug 5.
Published in final edited form as: J Am Chem Soc. 2009 Aug 5;131(30):10567–10573. doi: 10.1021/ja902896e

Table 1.

Kinetics of YD • reduction in 2H2O, as assessed by EPR spectroscopy.a

Mole Fraction
2H2O		 Rate Constant
(10−4 s−1)		 Relative
Amplitude (%)		 EPR Signal Intensityb
[ARB.U./(mg chl/mL)]		 Rate Relative
to 100% 2H2O
0 5.90 ± 0.43 92 ± 4 22600 ± 1600 3.47 ± 0.55 (KIE)
20 4.10 ± 0.73 91 ± 6 21400 ± 970 2.41 ± 0.55
30 3.35 ± 0.39 89 ± 5 23700 ± 2200 1.97 ± 0.36
40 3.13 ± 0.22 94 ± 1 21600 ± 1700 1.84 ± 0.29
50 2.84 ± 0.56 92 ± 2 21500 ± 2200 1.67 ± 0.40
60 2.23 ± 0.60 91 ± 3 21100 ± 1200 1.31 ± 0.40
70 2.57 ± 0.15 94 ± 2 20400 ± 3100 1.51 ± 0.23
100 1.70 ± 0.24 95 ± 3 20300 ± 1600 1.00 ± 0.34
a

The means are the average of 6–8 samples. The error is reported as ± one standard deviation. All samples contained 10 µM DCMU to inhibit QB − formation. The transients were fit to a biexponential decay using IGOR Pro software (Wavemetrics, Lake Oswego, OR). The quality of the least squares fit was determined by the χ2 value.

b

Signal intensity at 56 s, in arbitrary units.