<prompt> Biotin is required for the activity ofPyruvate carboxylaseLactate dehydrogenaseSuccinate thiokinasePhosphohexose isomerase  <response>: Mitochondrial pyruvate carboxylase catalyzes the carboxylation of pyruvate to oxaloacetate, an ATP- requiring reaction in which the vitamin biotin is the coenzyme.Biotin binds CO2 from bicarbonate as carboxybiotin prior to the addition of the CO2 to pyruvate.The resultant oxaloacetate is reduced to malate, exported from the mitochondrion into the cytosol and there oxidized back to oxaloacetate.Key Concept:Biotin is the co-enzyme for pyruvate carboxylase which carboxylates pyruvate into oxaloacetateRef : Harpers illustrated biochemistry, 31st edition. 