Abstract
Homogeneous catalytic hydrogenation was used to modify the level of fatty acid unsaturation of thylakoid membranes in the pea chloroplast. Fluidity alteration has been monitored simultaneously using the spin-label probe, 16-doxyl stearate. Even in the case of 30% hydrogenation, no change in the reduction rate of flash-oxidized cytochrome f was observed, in contrast to the fact that the same decrease in the double-bond content of the thylakoid membrane resulted in a pronounced inhibition in the full-chain electron transport. We conclude that the rate of lateral diffusion of reduced plastoquinone is unaffected by the lowering of the fluidity of the thylakoid lipid matrix.