Nitroxyl fatty acid probes inserted into the chloroplast membranes have been used to study the process of evolution of oxygen by chloroplasts. From the kinetics of the reduction of the nitroxyls on exposure to continuous illumination at two values of u.h.f. power the authors have determined the products ke[O2] where ke is the spin exchange constant of nitroxyl and oxygen; [O2] is the oxygen concentration. It is shown that unlike liposomes, in the chloroplast membranes there is no oxygen in the dark. This is possible as a result of oxygen uptake in the different biochemical processes. On illumination of the chloroplasts the oxygen evolved is detected, the maximum value ke[O2]=1·2 × 105 sec-1 being observed at the centre of the membrane. At temperatures above 40 and below -20 °C oxygen is not evolved.
|Number of pages||6|
|Publication status||Published - Dec 1 1988|
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