SEARCH

SEARCH BY CITATION

SUMMARY

The uptake of 2-oxoglutarate and pyruvate by intact, isolated pea chloroplasts has been studied by centrifugal filtration. Inhibition of 2-oxoglutarate transport by malate, fumarate, oxaloacetate and glutamate suggested that a dicarboxylate carrier is operating. This carrier is substrate saturated at approximately 1 mM and shows a Vmax of 32 μmol (mg chlorophyll)-1 h-1 and has a Km of 0·19 mM. Pyruvate enters pea chloroplasts mainly by diffusion, but at low external concentrations of the keto-acid uptake may be carrier mediated with a Vmax of 6·5 μmol (mg chlorophyll)-1 h-1 and a Km of 0·33 mM. A number of compounds related to pyruvate, and also α-cyano-4-hydroxycinnamic acid, failed to inhibit pyruvate movement.