Electrochromic Absorption Change in Chloroplasts

REDOX TITRATIOJS OF THE FAST AND SLOW PHASE OF THE 515NM ELECTROCHROMIC ABSORPTION CHANGE IN CHLOROPLASTS 

LINDA GIORGI, NIGEL PACKHAM AND JAMES BARBER 

ARC Photosynthesis Research Group, Department of Pure and Applied Biology, Imperial College, London SW7 2BB (England). 

The fast phase (phase a) of the 515 nm electrochromic absorption change, AA515, occurs as a result of the transmembrane electric field set up at the photochemical reaction centres upon flash activation (Witt 1979). 

1(b)) indicating that the electron transfer step responsible for phase b is related to the oxidation of quinol by the Rieske FeS centre located within the cytochrome b-f complex. Subtraction of signals DBMIB reveals 

---