title: Coenzyme models. 10. Rapid oxidation of NADH by a flavin immobilized in cationic polyelectrolytes.
abstract: The title flavin rapidly oxidizes NADH, the observed enhancement being of 460--4650-fold compared with 3-methyltetra-O-acetylriboflavin. Analysis of the kinetic data at 30 degrees C established that the reaction proceeds according to the Michaelis-Menten kinetics at low ionic strength (mu = 0.02: Km = ca. 10(-5) M, kact. = 0.06-0.37 s-1) and according to the simple second-order kinetics at high ionic strength (mu = 0.3), the largest rate difference being 342-fold. On the other hand, the oxidation of 1-benzyl-1,4-dihydronicotinamide, a NADH model compound, was not accelerated by the use of the title flavin. It is concluded, therefore, that the formation of the polymeric flavin-NADH complexes due to the electrostatic interaction is responsible for the marked rate enhancement. This is the first example that the oxidation of NADH is facilitated in the nonenzymatic system.
mesh_terms: D005415:Flavins; D007700:Kinetics; D009243:NAD; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D011108:Polymers; D012256:Riboflavin / Q000031:analogs & derivatives
chemical_list: D005415:Flavins; D011108:Polymers; D009243:NAD; D012256:Riboflavin