Binding of oxalate to mitochondrial inner membranes of rat and human kidney.
Oxalate bound specifically to homogenates of rat kidney and liver but not to homogenates prepared from heart, lung, skeletal muscle, spleen, stomach, small or large intestine. In the renal cortex, binding was localized to the inner mitochondrial membrane where it was enriched fourfold when compared to homogenate. Binding of the oxalate reached equilibrium in two minutes at 23C. Analysis of the binding sites by Scatchard plot indicated that the maximum binding capacity was 49 pmol./mg. protein and the apparent dissociation constant (Kd) was 43 nM. The IC50 of oxalate was 0.25 microM. Among the inhibitors studied the IC50 was in the following order: oxalate less than oxamate less than parabanate less than glyoxalate less than oxaloacetate less than malate less than citrate = glycollate. Heat and treatment with lubrol abolished the binding completely. Binding was not enhanced by the presence of calcium in the incubation medium; neither was it inhibited by the presence of calcium together with its transport inhibitors. A binding substance with some characteristics similar to the rat mitochondrial binding factor was also found in the human renal cortex.
D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D010070:Oxalates / Q000378:metabolism*; D019815:Oxalic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
D002352:Carrier Proteins; D010070:Oxalates; D019815:Oxalic Acid