5-Hydroxytryptophan as a precursor of a catalyst for the oxidation of NADH. 2005

Noemí de-los-Santos-Alvarez, and María Jesús Lobo-Castañón, and Arturo J Miranda-Ordieres, and Paulino Tuñón-Blanco, and Héctor D Abruña
Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.

Following oxidation of 5-hydroxytryptophan (5-HTPP) at a pyrolytic graphite electrode at pH 7.5, two quasi-reversible redox couples emerge at -0.170 and +0.032 V, respectively, due to oxidation products strongly adsorbed to the electrode surface. These redox processes have been electrochemically and kinetically characterized in terms of the dependence of the formal potential (E degrees ') with pH, variation of the current density with scan rate, operational stability, and electron-transfer rate constant (k(s)). The wave centered at +0.032 V could mediate the oxidation of NADH, exhibiting a strong and persistent electrocatalytic response. A quinone-imine structure has been proposed as the electrocatalytically active species. The kinetics of the reaction between the mediator and NADH has been characterized via rotating disk electrode voltammetry, and it has been found that the rate constant for the reaction is dependent on the solution concentration of NADH. 5-HTPP modified electrodes could be employed in the amperometric detection of NADH with a limit of detection in the nanomolar range. Moreover, 5-HTPP modified electrodes retain their electrocatalytic activity for at least one week. The potential application of these electrodes to amperometric biosensor is demonstrated.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D009243 NAD A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed) Coenzyme I,DPN,Diphosphopyridine Nucleotide,Nadide,Nicotinamide-Adenine Dinucleotide,Dihydronicotinamide Adenine Dinucleotide,NADH,Adenine Dinucleotide, Dihydronicotinamide,Dinucleotide, Dihydronicotinamide Adenine,Dinucleotide, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide,Nucleotide, Diphosphopyridine
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D002384 Catalysis The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction. Catalyses
D004563 Electrochemistry The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes. Electrochemistries
D004566 Electrodes Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. Anode,Anode Materials,Cathode,Cathode Materials,Anode Material,Anodes,Cathode Material,Cathodes,Electrode,Material, Anode,Material, Cathode
D004579 Electron Transport The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270) Respiratory Chain,Chain, Respiratory,Chains, Respiratory,Respiratory Chains,Transport, Electron
D004867 Equipment Design Methods and patterns of fabricating machines and related hardware. Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D006108 Graphite An allotropic form of carbon that is used in pencils, as a lubricant, and in matches and explosives. It is obtained by mining and its dust can cause lung irritation. Graphene
D006916 5-Hydroxytryptophan The immediate precursor in the biosynthesis of SEROTONIN from tryptophan. It is used as an antiepileptic and antidepressant. 5-HTP,Hydroxytryptophan,Oxitriptan,Oxytryptophan,Tryptophan, 5-Hydroxy-,5 Hydroxytryptophan,5-Hydroxy- Tryptophan,Tryptophan, 5 Hydroxy

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