title: Beta-oxidation as channeled reaction linked to citric acid cycle: evidence from measurements of mitochondrial pyruvate oxidation during fatty acid degradation.
abstract: 1. The kinetics of mitochondrial mammalian pyruvate dehydrogenase multienzyme complex (PDHC) is studied by the formation of CO2 using tracer amounts of [1-14C]pyruvate. It is found that the Hill plot results in a (pseudo-)cooperativity with a transition of n-1----3 at a pyruvate concentration about Ks. 2. Addition of L-carnitine, octanoate, palmitoyl-CoA or palmitate + L-carnitine + fatty acid-binding protein results in a Hill coefficient of n = 2 following the kinetics of pyruvate oxidation. 3. Addition of fatty acid-binding protein to an assay system oxidizing palmitate in presence of L-carnitine alters the pattern of the kinetics in the Hill plot so that an apparently lower level of L-carnitine is necessary for the reaction course of beta-degradation. 4. It is concluded that beta-degradation is a coordinated, multienzyme-complex based mechanism tightly linked to citric acid cycle and it is proposed that L-carnitine is actively involved into the reaction and not only functioning as carrier-molecule for transmembrane transport.
authors.affiliation: Institut für Physiologische Chemie II, Heinrich-Heine-Universität Düsseldorf, Fed. Rep. Germany.
authors.forename: M E
authors.initials: ME
authors.lastname: Förster
authors.forename: W
authors.initials: W
authors.lastname: Staib
mesh_terms: D000818:Animals; D002952:Citric Acid Cycle / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000378:metabolism*; D019289:Pyruvic Acid; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005227:Fatty Acids; D011773:Pyruvates; D019289:Pyruvic Acid