Electrocatalytic Oxidation of NADH by Oxidized s-Adenosyl-L-Methionine (SAMe): Application to NADH and SAMe Determinations
✍ Scribed by Noemí de-los-Santos-Álvarez; María Jesús Lobo-Castañón; Arturo J. Miranda-Ordieres; Paulino Tuñón-Blanco
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 106 KB
- Volume
- 16
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
Abstract
s‐Adenosyl‐L‐methionine (SAMe) is an adenosine analogue with therapeutical activity against affective disorders and liver dysfunctions. It can be oxidized on graphite electrode yielding a strongly adsorbed electroactive oxidation product for which a quinone‐imine structure is proposed. This compound is capable of electrocatalyzing the NADH oxidation at low potentials, lowering the overvoltage by about 300 mV. An amperometric method for NADH determination at +0.1 V (Ag|AgCl|KCl~sat~) is developed using an oxidized‐SAMe‐modified electrode in pH 9. Linear calibration plots were obtained with a detection limit of 2.4 nM. The electrode response time and the relative standard deviation of the slope of the calibration plot for 5 different modified electrodes were 12 s and 5.6% respectively. The catalytic scheme also provides the first method to determine SAMe itself by adsorptive differential pulse voltammetry. The linear range was found to be 42.4–424 nM with a reproducibility of 6.9%. The method was applied to SAMe determination in a pharmaceutical formulation.