+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: a pulsed photoacoustic study of electron transfer in photosystem I reveals a similarity to bacterial reaction centers in both volume change and entropy



Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: a pulsed photoacoustic study of electron transfer in photosystem I reveals a similarity to bacterial reaction centers in both volume change and entropy



Biochemistry (American Chemical Society) 40(24): 09-16



The thermodynamic properties of electron transfer in biological systems are far less known in comparison with that of their kinetics. In this paper the enthalpy and entropy of electron transfer in the purified photosystem I trimer complexes from Synechocystis sp. PCC 6803 have been studied, using pulsed time-resolved photoacoustics on the 1 ms time scale. The volume contraction of reaction centers of photosystem I, which results directly from the light-induced charge separation forming P700+FA/FB- from the excited-state P700*, is determined to be -26 [plus or minus] 2 A3. The enthalpy of the above electron-transfer reaction is found to be -0.39 [plus or minus] 0.1 eV. Photoacoustic estimation of the quantum yield of photochemistry in the purified photosystem I trimer complex showed it to be close to unity. Taking the free energy of the above reaction as the difference of their redox potentials in situ allows us to calculate an apparent entropy change (TDS) of +0.35 [plus or minus] 0.1 eV. These values of dV and TDS are similar to those of bacterial reaction centers. The unexpected sign of entropy of electron transfer is tentatively assigned, as in the bacterial case, to the escape of counterions from the surface of the particles. The apparent entropy change of electron transfer in biological system is significant and cannot be neglected. Reprinted by permission of the publisher.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 010015356

Download citation: RISBibTeXText

PMID: 11401556

DOI: 10.1021/bi0103720


Related references

Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: volume change, enthalpy, and entropy of electron-transfer reactions in manganese-depleted photosystem II core complexes. Biochemistry (American Chemical Society) 40(24): 17-25, 2001

Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: volume change, enthalpy, and entropy of electron-transfer reactions in the intact cells of the cyanobacterium Synechocystis PCC 6803. Biochemistry 40(24): 7126-7132, 2001

Primary electron transfer processes in photosynthetic reaction centers from oxygenic organisms. Photosynthesis Research 125(1-2): 51-63, 2015

Calculated protein and proton motions coupled to electron transfer: electron transfer from QA- to QB in bacterial photosynthetic reaction centers. Biochemistry 38(26): 8253-8270, 1999

Kinetics and thermodynamics of electron transport reactions in biological systems 5. transitional characteristics of electron transfer in photosynthetic reaction centers. Biologicheskie Nauki (Moscow) (8): 5-18, 1985

Enthalpy/entropy driven activation of the first interquinone electron transfer in bacterial photosynthetic reaction centers embedded in vesicles of physiologically important phospholipids. Bioelectrochemistry 70(1): 18-22, 2007

Kinetics and thermodynamics of electron transport reactions in biological systems 3. electron transfer in photosynthetic reaction centers impulse regime of excitation. Biologicheskie Nauki (Moscow) (8): 5-16, 1981

Picosecond kinetics of the initial photochemical electron-transfer reaction in bacterial photosynthetic reaction centers. Biochemistry 24(26): 7516-7521, 1985

Temperature independence of the primary electron transfer reaction rate constants in photosynthetic bacterial reaction centers. Doklady. Biochemistry and Biophysics 440: 234-238, 2011

Pathway of proton transfer in bacterial reaction centers: second-site mutation Asn-M44- >Asp restores electron and proton transfer in reaction centers from the photosynthetically deficient Asp-L213- >Asn mutant of Rhodobacter sphaeroides. Proceedings of the National Academy of Sciences of the United States of America 90: 25-9, 1993

Pathway of proton transfer in bacterial reaction centers: second-site mutation Asn-M44-->Asp restores electron and proton transfer in reaction centers from the photosynthetically deficient Asp-L213-->Asn mutant of Rhodobacter sphaeroides. Proceedings of the National Academy of Sciences of the United States of America 90(4): 1325-1329, 1993

The kinetics and thermodynamics of early electron transfer in bacterial reaction centers. Photochemistry and Photobiology 59(SPEC ISSUE): 53S, 1994

Electron acceptors of bacterial photosynthetic reaction centers. II. H+ binding coupled to secondary electron transfer in the quinone acceptor complex. Biochimica et Biophysica Acta 548(2): 309-327, 1979

Exploring the Energy Profile of the Q A - to Q B Electron Transfer Reaction in Bacterial Photosynthetic Reaction Centers: pH Dependence of the Conformational Gating Step. Biochemistry 41(8): 2694-2701, 2002

Exploring the energy profile of the Q(A)(-) to Q(B) electron transfer reaction in bacterial photosynthetic reaction centers: pH dependence of the conformational gating step. Biochemistry 41(8): 2694-2701, 2002