67 and 0.33, respectively, which

is in fair agreement with the portions determined using Method 1 (see Table 2). For the LDAO sample of Fig. 3 (see fitting parameters in Tables 2), the α parameter values obtained with Methods 1 and 2 are the same and equal to ≈0.82 cm2/mW s. The Q B -depleted to Q B -active check details ratios are 0.23–0.77 using Method 1, and 0.36–0.64 from the analysis of the single flash-activated dark decay kinetics. The \( k^\prime_\textrec \) value obtained using Method 2, 1.06 s−1, is close to the value of 1.18 s−1 calculated from the single flash dark recovery kinetics using \( k^\prime_\textrec \) from Eq. 6. Although neither modeling scheme worked perfectly well for the membrane-bound RCs, Method 2 produced reasonably good results. Complications may arise

with the membrane Selleck GDC-0994 samples due to strong light scattering, which simultaneously produces two competitive effects—a pronounced decrease in the light intensity along the excitation beam (scattering attenuation) and an increased photoexcitation intensity due to multiple scattering. The light parameter α obtained for the sample with membranes is approximately 10 times bigger than that for isolated RCs (6.3 mW−1 cm2 s−1 and higher for membrane-bound RCs), which is in agreement with our previous studies showing that Adriamycin cost the efficiency of photoexcitation increases significantly in membranes due to the light scattering effects (Goushcha et al. 2004). Our estimation of the excitation beam intensity in the middle of the cuvette with membranes is approximate and based upon previous studies using the same experimental

setup (same sample concentration, same excitation and monitoring conditions, and same cuvette path length). The ADAM7 competition between scattering attenuation and increased excitation due to multiple scattering may vary depending upon path length, concentration, and excitation/monitoring conditions for membrane samples. The relationship between I and I exp given in the Appendix, with the scaling parameter written in terms of the dipole transition matrix, supports the apparent relation between scattering attenuation and an increased effective photoexcitation. From the above experimental results, the \( k^\prime_\textrec \) value obtained for the membrane samples using Method 2 (≈0.82 s−1) is larger than the value of the recombination rate constant (≈0.22 s−1) measured using the single flash activated recovery kinetics. The difference should be attributed to two reasons: (1) uncertainty in determination of I exp using Method 2 due to scattering effects and (2) long lifetime of the charge separated state for membrane-bound RCs (~3–5 s, see Goushcha et al. 2004), which means that the 2-second exposure time in our experiments may not have been long enough for the correct determination of the rate constants. Taking these precautions into consideration, we used the measured value \( k^\prime_\textrec = 0.