1. Volume 78, Issue 5, Pages 2581-2589 (May 2000)
Aspartate 75 Mutation in Sensory Rhodopsin II from Natronobacterium pharaonis Does Not Influence the Production of the K-Like Intermediate, but Strongly Affects Its Relaxation Pathway 
Aba Losi, Ansgar A. Wegener, Martin Engelhard, Wolfgang Gärtner, Silvia E. Braslavsky 
Biophysical Journal 
Volume 78, Issue 5, Pages (May 2000)
DOI: /S (00)
Copyright © 2000 The Biophysical Society Terms and Conditions

2. Figure 1
pH Titration of pSRII-D75N in (top) PML 20:1 and (bottom) DM. The titration curves were built by using the absorption at (●) 520 and (○) 390nm as parameters. The increasing of the band at 390nm indicates the appearance of the deprotonated SB. The experimental data points were fitted using Eq. 2.
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3. Figure 2
LIOAS signal for pSRII-D75N in PML 20:1 at T=6.5°C, λexc=532nm. Inset: deconvolution results. At this relatively low temperature, the two consecutive expansions accompanying the formation and decay of KE are the main contributions to the signal. Reference: bromocresol green.
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4. Figure 3
Arrhenius plot for the rate constant, k2, of the KE → KL decay as measured by LIOAS in (○) DM-solubilized and (●) PML (20:1)-reconstituted pSRII-D75N. The decay is not thermally activated in the range 6.5–52°C. Error bars correspond to the dispersion of four independent experiments.
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5. Figure 4
Plot of the LIOAS amplitudes associated with (■) formation and (○) decay of KE in DM samples. The amplitudes were corrected for the temperature dependence of the absorbance at λexc=532nm. Inset: absorption spectra at (——) 20 and ( ) 52°C. The thermally induced optical change is completely reversible.
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6. Figure 5
(——) Absorption and ( ) fluorescence spectrum of pSRII-D75N in DM. λexc=510nm, T=6.5°C. The fluorescence spectrum was normalized to the absorption maximum.
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7. Figure 6
Flash photolysis determination of ΦK in PML-reconstituted pSRII-D75N. Top: bleaching of the parent state at 510nm (bottom line) and absorption of K565 at 610nm. Bottom: plots of ΔA versus incident energy for (□), TPPS T-T absorption monitored as the amplitude at 460nm immediately after the laser pulse; (●) formation of K565 in pSRII-D75N at 610nm, and (○) bleaching of pSRII-D75N parent state at 510nm. For pSRII-D75N, the average value of ΔA between 0.5 and 6μs was taken. On this time scale, K565 appears as a permanent product (top). At the maximum fluence of 200μJ, 2% of the molecules in the illuminated volume were photoconverted to K565 intermediate.
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8. Figure 7
Enthalpy profile and structural volume changes for the early steps of the pSRII-D75N photocycle. The 400-ns decay of KE is optically silent in our transient absorption experiment. KL thermal decay is outside the LIOAS window. The 565 transient absorbance decay (Schmies et al., 2000) is attributed to the decay from KE.
Biophysical Journal  , DOI: ( /S (00) )
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