The significance of the kinetic analysis of fluorescence induction in DCMU‐inhibited chloroplasts in terms of photosystem 2 connectivity and heterogeneity

FEBS Letters

Hodges, M.¹  Barber, J.¹ 

[1] ARC Photosynthesis Research Group, Department of Pure and Applied Biology, Imperial College, London SW7 2BB, England

关键词: Photosynthesis;    Chlorophyll fluorescence;    Induction curve;    Biphasic kinetics;    Membrane organisation;    Structural heterogeneity;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethyl urea;    LHCP;    light-harvesting chlorophyll a/b-protein complex;    PS;    photosystem;    Q;    primary acceptor of photosystem 2;    F m;    maximum fluorescence;    F o;    initial fluorescence;    F v;    F m − F o;    A max;    unnormalised area over induction curves;    A norm;    normalised A max;   

DOI  :  10.1016/0014-5793(83)80961-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A study has been made on the slow component (β_max) of chlorophyll fluorescence induction curves exhibited by DCMU-inhibited pea thylakoids. In the absence of high levels of screening cations, β_max is high and the fluorescence yield low, while the addition of K⁺, Mg²⁺ or Tris(ethylenediamine) cobaltic(III) cation (TEC³⁺) decreases β_max and increases fluorescence yield. These changes are inhibited when the thylakoids are fixed with glutaraldehyde. By comparing cation- and light-harvesting chlorophyll a/b-protein (LHCP) phosphorylation-induced changes it can be seen that β_max correlates with changes in the overall kinetics of photosystem (PS) 2 photoreduction, as indicated from the normalised area over the induction curve (Anorm). When the plastoquinone (PQ) pool is chemically reduced by dithionite, prior to the initiation of the curve, both F _o and F _m are increased and the slow component removed. These observations are used to question the concept of two structurally distinct PS2 centres [Arch. Biochem. Biophys. (1978) 190, 523–530] and to discuss the use of β_max in monitoring PS2 organisation.

【 授权许可】

Unknown