Kinetic measurements of electron transfer in coupled chromatophores from photosynthetic bacteria A method of correction for the electrochromic effects

FEBS Letters

Crofts, Antony R.²  Virgili, Marco¹  Melandri, B.Andrea¹  Venturoli, Giovanni¹ 

[1] Dipartimento di Biologia, Istituto ed Orto Botanico, Universitá di Bologna, via Irnerio 42, 40126 Bologna, Italy;Department of Physiology and Biophysics, University of Illinois at Urbana-Champaign, 524 Burril Hall, 407 S. Goodwin Avenue, Urbana, IL 61801, USA

关键词: Electron transfer;    Membrane potential;    Bacterial photosynthesis;    Electrochromism;    Carotenoid;    Bacteriochlorophyll;    BChl;    bacteriochlorophyll;    cyt;    cytochrome;    DAD;    diaminodurene (2;    3;    5;    6-tetramethyl-p-phenylenediamine);    Mops;    4-morpholineethanesulfonic acid;    PMS;    N-methylphenazonium methosulfate;    RC;    reaction center;   

DOI  :  10.1016/0014-5793(87)80276-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A quantitative study of the kinetics of electron transfer under coupled conditions in photosynthetic bacteria has so far been prevented by overlap of the electrochromic signals of carotenoids and bacteriochlorophyll with the absorbance changes of cytochromes and reaction centers. In this paper a method is presented by which the electrochromic contribution at any wavelength can be calculated from the electrochromic signal recorded at 505 nm, using a set of empirically determined polynomial functions. The electrochromic contribution to kinetic changes at any wavelength can then be subtracted to leave the true kinetics of the redox changes. The corrected redox changes of the reaction center measured at 542 and 605 nm mutually agree, thus providing an excellent test of self-consistency of the method. The corrected traces for reaction center and of cytochrome b-566 demonstrate large effects of the membrane potential on the rate and poise of electron transfer. It will now be possible to study the interrelation between proton gradient and individual electron transfer reactions under flash or steady-state illumination.

【 授权许可】

Unknown