Supporting Information

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1 Supporting Information Lipid-Controlled Stabilization of Charge-Separated States (P + Q B ) and Photocurrent Generation Activity of a Light-Harvesting Reaction Center Core Complex (LH1-RC) from Rhodopseudomonas palustris Tomoyasu Noji, 1 Mikano Matsuo, 2 Nobutaka Takeda, 3 Ayumi Sumino, 2 Masaharu Kondo, 3 Mamoru Nango, 1 Shigeru Itoh, 4 and Takehisa Dewa, 2,3,* 1 The OCU Advanced Research Institute for Natural Science & Technology (OCARINA), Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka , Japan 2 Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, , Japan 3 Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, , Japan 4 Division of Material Sciences (Physics), Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya , Japan Table of Contents page Quenching of LH1-RC by UQ 0 : Stern Volmer analysis and correction of fluorescence yield. S2 Figure S1. Stern Volmer plots representing the effects of UQ 0 on enhancement and quenching of fluorescence of LH1-RC. S3 Figure S2. Absorption and fluorescence spectra of LH1-RC in various environments. S4 Figure S3. Relative fluorescence yield of LH1-RC in various environments as a function of the PFD. S5 Figure S4. Steady-state light minus dark difference absorption spectrum of LH1-RC. S6 Figure S5. Kinetics for charge recombination (P + Q ) in LH1-RC under various environments. S7 Figure S6. Kinetics for charge recombination (P + Q ) of LH1-RC in the presence of 10 mm o-phenanthroline. S8 Figure S7. Dependence of the photocurrent density on the concentration of mediators cyt c and UQ 0. S8 Figure S8. Absorption and action spectra of LH1-RC assembled onto an ITO electrode. S9 Derivation of the formula of F v /F from the steady-state approximation. S10 Figure S9. Kinetic diagram of the photochemical process including accessory BChl a, B, and bacteriopheophytin, H. S12 Derivation of k 1 from the steady-state approximation for photocurrent generation. S12 Figure S10. Correlation between photo-receptivity to F v /F and stability of charge-separated state for various systems. S13 Figure S11. Wide-area AFM images of NH 2 -ITO and DOPG-membrane. S14 S1

2 Quenching of LH1-RC by UQ 0 : Stern Volmer analysis and correction of fluorescence yield. UQ 0 itself non-photochemically quenches the fluorescence of LH1. Figure S1A shows a Stern Volmer plot for LH1-RC as a function of the concentration of UQ 0 in the system of DDM micellar solution. The ratio of fluorescence intensity, I 0 /I, where I 0 and I represent fluorescence intensities of LH1-RC under the conditions of ( ) and (+) UQ 0, respectively, decreases below 1 in the concentration range of 0 1 mm and increased above 1 mm. This indicates that UQ 0 in the low concentration < 1mM helps to stabilize the closed state of LH1-RC, resulting in enhanced emission, and UQ 0 above 1 mm mainly contributes to quenching of LH1 emission in a linear manner. Such a quenching effect of UQ 0 was observed in the DDM-micelle, DOPG-micelle, DOPG-vesicle, and DOPC-vesicle systems as shown in Figure S1A D. Subtracting the contribution of quenching as the linear function from observed (I 0 /I) obs, that is, (I 0 /I) obs a [UQ 0 ], where a represents the slope of the linear function, yields the corrected (I 0 /I) corr, exhibiting constant I 0 /I value in the concentration range > 1 mm. Based on this result, hereafter we chose 1 mm UQ 0 for the (+) UQ 0 condition making LH1-RC in the closed state and used fluorescence intensities corrected through this Stern Volmer relationship, (I 0 /I) corr = (I 0 /I) obs a [UQ 0 ]. Note that UQ 10 with the longer hydrophobic tail more significantly quenches LH1 emission than UQ 0. Quinones bound to LH1 may quench the emission. For other systems, i.e., DOPG-micelle, DOPG-vesicle, and DOPC-vesicles, the fluorescence yield was corrected in the same manner as shown in Figure S1B D. In the case of chromatophores from Rsp. rubrum S1 (E), only quenching was observed. As a result, the PFD-dependent fluorescence yield for the chromatophore system exhibited the higher fluorescence yield in the absence of UQ 0 than that in the presence of UQ 0 as shown in Figure S3D. S2

3 Figure S1. Stern Volmer plots representing the effects of UQ 0 on enhancement and quenching of fluorescence of LH1-RC in a DDM micelle (A), DOPG-micelle (B), DOPG-vesicle (C), and DOPC-vesicle (D), and chromatophores from Rsp. rubrum S1 (E) solutions without stirring.!, observed (I 0 /I) obs where I 0 and I represent fluorescence intensity of LH1-RC in the absence and presence of UQ 0, respectively; ", corrected I 0 /I, (I 0 /I) corr = (I 0 /I) obs a [UQ 0 ], where a represents the slope of the linear function. S3

4 Figure S2. Absorption (A) and fluorescence spectra (B) of LH1-RC in various environments of Tris-HCl solution (20 mm, ph 8.6): (i: black), in DDM-micelle; (ii, red), in DOPG-micelle; (iii, green), in DOPG-vesicle; (iv, blue), DOPC-vesicle. Spectra were acquired at room temperature. S4

5 Figure S3. Relative fluorescence yield of LH1-RC in various environments as a function of the PFD. A, DOPG-micelle; B, DOPG-vesicle; C, DOPC-vesicle; D, chromatophores from Rsp. rubrum S1. Solution conditions:!, (+) stirring/( ) UQ 0 ; r, ( ) stirring/( ) UQ 0 ; ", ( ) stirring/(+) UQ 0. Inset: expansion of the low PFD region. S5

6 Figure S4. Steady-state light minus dark difference absorption spectrum of LH1-RC dissolved in the TL buffer solution. The spectrum acquired at room temperature. The light-minus-dark spectrum was measured by a spectrophotometer with optical fibers (EPP2000-VIS-50, Stellar-Net, Inc., Tampa, FL, USA). Light sources of a solar simulator (100 mw cm 2 ) (OTENTO-SUN II; Bunkoukeiki) and a deuterium/halogen light source (SL5; Stellar-Net, Inc.) were used as excitation and probe lights, respectively, which were aligned perpendicularly. S6

7 Figure S5. Kinetics for charge recombination (P + Q ) in LH1-RC under various environments. (A), DDM-micelle; (B), DOPG-micelle; (C), DOPG-vesicle; (D), DOPC-vesicle; (E), chromatophore of Rsp. rubrum S1.Gray and black lines show experimental raw data and fitting curves calculated by multi-component exponential functions, respectively. The indexes in the figures, 1 and 2, represent the experimental conditions, ( ) and (+) UQ 0, respectively. S7

8 Figure S6.Kinetics for charge recombination (P + Q ) of LH1-RC in the presence of 10 mm o-phenanthroline. (A), DDM-micelle; (B), DOPG-micelle; (C), DOPG-vesicle; (D), DOPC-vesicle; (E), chromatophore of Rsp. rubrum S1. Gray and black lines show experimental raw data and fitting curves calculated by multi-component exponential functions, respectively. Figure S7. Concentration dependence of mediators cyt c and UQ 0 on photocurrent density. The molar ratio of cyt c/uq 0 was fixed at 5. The electrode used was LH1-RC reconstituted into DOPG S8

9 membrane. LH1-RC/DOPG = 1/250 (mol/mol). [LH1-RC] on the electrode was 13.6 nmol m -2. Photo flux density: 60.6 µmol m -2 s -1. Figure S8. Absorption (solid line) and action spectra (red circle) of LH1-RC assembled onto an NH 2 -ITO electrode. LH1-RCs were reconstituted into DOPG lipid membrane. The dashed line represents the absorption spectrum of LH1-RC reconstituted in DOPG vesicles. [LH1-RC] on the electrode was 0.6 pmol cm -2. Photo flux density at 880 nm for the measurement of photocurrent was 7.8 µmol m -2 s -1. S9

10 Derivation of the formula of F v /F from the steady-state approximation. The rate constant of singlet decay of LH1*, k L, can be described as k! = k! + k! (S1) where k F and k D represent rate constants of emission and deactivate processes including an intersystem crossing to carotenoid and thermal deactivation. Fluorescence intensity, I F, is described as I! = Ak! LH1 PQ + [LH1 P! Q! ] (S2) where A represents a corrective constant with respect to instruments. Fluorescence yield, F, is given by I! F = J!" σn! LH1 RC! (S3) where J ex, σ, N A, and [LH1-RC] 0 represent the PFD of excitation, absorption cross-section of LH1, Avogadro number, and the initial concentration of LH1-RC. Given the steady-state approximation in which the rates of change in concentrations of all reaction species in Figure 7, (LH1-PQ) x as a generic representation, are negligibly small: d[(lh1 PQ)! ] dt = 0 (S4) I F is described by using the term [LH1-RC] 0 as follows. I! = Ak!J!" σn! [LH1 RC]! 1 + J!" σn! B k! + k! + k! + J!"σN! B k! + k! k! + k! + k! k! k! k! + k! (S5) where B represents a formula composed of rate constants. B = k! k! k! k! + k! k! + k! + k! k! k! (S6) Therefore, F = Ak! 1 + J!" σn! B k! + k! + k! + J!"σN! B k! + k! k! + k! + k! k! k! k! + k! (S7) Definition and input parameters of the rate constant are summarized in Table 4 in the text. F o and F m can be derived from S7 to consider the limit cases, J ex 0 and J ex, respectively: S10

11 F! = Ak! k! + k! + k! k! + k! k! + k! + k! k! k! S8 F! = Ak! k! + k! S9 The maximum quantum yield of charge separation, F v /F m, is described as F! F! = k! k! 1 + k! k! 6 k! k! k! k! + k! + k! Description of the yield of charge separation under various excitation intensities, F v /F, is F! F = 1 k! + k! + k! k! + k! J!" σn A k! k! + k! k! + k! k! + k! + k! k! k! k! + k! k! + k! + k! k! k! k! k! + k! k! + k! + k! + J!" σn! k! k! (7) Description for F v /F m and F v /F that were considered the actual electron transfer mediated by accessory BChl a (B) and bacteriopheophytin (H), as shown in Figure S9 can also be given. The F v /F m is same as (6) and the latter is F! F = 1 k!!! + k! + k! 1 k!!! + k! + k! k!!! + k! + k! k! + k! k! k! 1 + J!" σn A B! k!!! + k! + k! k! + k! k! k! + J!"σN! B! k! + k!!! (S10) where B' represents a formula composed of rate constants. k!! k! k! k! B = k! k! + k! k! + k! k 3 + k b + k 4 k! + k! k! k! (S11) The values of k r and k c obtained by the fitting analysis using eq. S10 are consistent with those from eq. 7 for the simplified system without the pigments in RC, i.e., B and H, indicating that the simpler eq. 7 sufficiently describes for the quantum yield of charge separation observed from the static fluorometry. S11

12 Figure S9. Kinetic diagram of the photochemical processes in LH1-RC including accessory BChl a, B, and bacteriopheophytin, H. Derivation of k 1 from the steady-state approximation for photocurrent generation. The steady-state approximation mentioned above was extended to the system of photocurrent generation. The reaction process was added to the steady state in the photochemical reaction shown in Figure 7. Through the equations S4 in the photocurrent generation reaction, v = k 2 α [LH1-(P + Q )] (S13) The relationship between [LH1-(P + Q )] and [LH1-(PQ)] can be derived as eq. S14 through the steady-state approximation. LH1 P! Q! = J!" σn! C LH1 PQ (S14) where C represents a formula composed of rate constants. C = k! k! k! + k! k! + k! k! + k! + k! k! k! S15 Eq. S13 can be described by using eq. S14 with the term [LH-(PQ)] 0 as v = k!α LH1 RC! J!" 1 σn! C + J!" (S16) S12

13 v = V!"#J!" K! + J!" (2) Therefore, V!"# = k! α LH1 RC! K! = k -1 + k 2 k! = 1 σn! C (S17) (S18) The rate constant k r is consistent with k -1 ; thus, K! = k! + k 2 k! = k! + k! k! + k! + k! k! + k! k! k! σn! k! k! (S19) Therefore, k! = σn! k! k! k! + k! + k! k! + k! k! k! S20 Figure S10. Correlation between photo-receptivity to F v /F and stability of charge-separated state for various systems. The photo-receptivity and stability of the charge-separated state were evaluated by I 1/2 and (τ mean ) -1, which represent the PFD at half of F v /F m and averaged rate constant of charge recombination, respectively. S13

14 Figure S11. Wide-area AFM images (5000 nm 5000 nm) of the NH 2 -ITO electrode (A) and LH1-RC-reconstituted planar PG membrane formed on the NH 2 -ITO electrode (B). Height profiles (i) and (ii) are shown for the lines indicated in the images. The profile (ii) was obtained through baseline compensation. The images were acquired in AC mode under ambient air (A) and aqueous conditions (B). The lipid/lh1-rc ratio was 250/1 (mol/mol) in B. No unruptured vesicles were observed on the electrode, indicating the vesicle to planar membrane transformation. S14