A Tris‐induced change in the midpoint potential of Z, the donor to photosystem II, as determined by the kinetics of the back reaction

FEBS Letters

Babcock, Gerald T.²  Yerkes, Christine T.¹  Crofts, Antony R.¹ 

[1] Department of Physiology and Biophysics, University of Illinois, 524 Burrill Hall, 407 S. Goodwin, Urbana, IL 61801, USA;Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA

关键词: Tris-washed chloroplasts;    Photosystem II;    EPR signal IIf;    Back reaction;    pH effect;    ADRY reagent;    ADRY;    reagents which accelerate the deactivation reactions of the water-splitting enzyme;    Y;    CCCP;    carbonylcyanide-m-chlorophenylhydrazone;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    EDTA;    ethylenediaminetetraacetic acid;    EPR;    electron paramagnetic resonance;    H;    magnetic field;    HEPES;    N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid;    MES;    2(N-morpholino)ethanesulfonic acid;    NADP;    nicotinamide adenine dinucleotide phosphate;    PS II;    photosystem II;    QA;    primary stable PS II acceptor;    Tricine;    N-tris(hydroxymethyl)methylglycine;    X″;    magnetic susceptibility;    Z;    primary donor to P680 in non O2-evolving chloroplasts;   

DOI  :  10.1016/0014-5793(83)80613-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A new method of measuring the rate of the back reaction from the state Z⁺ P680 Q_A ⁻ in Tris-washed chloroplasts is described. By using ratios of back reaction rates we demonstrate a Tris-induced change in the equilibrium between Z and P680 and attribute this change to an alteration of the midpoint potential of Z by Tris treatment. We also demonstrate that the previously observed inhibition of the back reaction by ADRY reagents can be localized at Z and understood in terms of electron donation to Z⁺ by ADRY reagents.

【 授权许可】

Unknown