title: A study on the physical interaction between the pyruvate dehydrogenase complex and citrate synthase.
abstract: In this paper, physicochemical evidence is given for the association between the pyruvate dehydrogenase complex (EC 1.2.4.1) and citrate synthase (EC 4.1.3.7) with two gel chromatographic techniques with poly(ethylene glycol) co-precipitation and with ultracentrifugation. Experiments with active enzyme gel chromatography indicate that citrate synthase also associates with pyruvate dehydrogenase complex in its functioning state. Citrate synthase binds to the isolated transacetylase core of pyruvate dehydrogenase complex, but in the binding to the whole pyruvate dehydrogenase complex the two other components of the complex are also involved. One pyruvate dehydrogenase complex can bind 10-11 citrate synthase dimers, and the dissociation constant is about 5.7-6.0 microM as determined by two independent methods. The association between the pyruvate dehydrogenase complex and citrate synthase raises the possibility of the dynamic compartmentation of acetyl-CoA in the mitochondria which results in the direction of acetyl-CoA from pyruvate towards citrate.
mesh_terms: D000818:Animals; D011232:Chemical Precipitation; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D046911:Macromolecular Substances; D008929:Mitochondria, Heart / Q000201:enzymology; D008970:Molecular Weight; D007652:Oxo-Acid-Lyases / Q000378:metabolism*; D011092:Polyethylene Glycols; D011485:Protein Binding; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D013552:Swine
chemical_list: D046911:Macromolecular Substances; D011768:Pyruvate Dehydrogenase Complex; D011092:Polyethylene Glycols; D002950:Citrate (si)-Synthase; D007652:Oxo-Acid-Lyases