58001-40-4

Upstream product

• 53-84-9 NAD 
• 865-05-4 β-nicotinamide adenine dinucleotide 
• 865-05-4 nicotinamide-adenin-dinucleotide oxidized 

Relevant academic research and scientific papers

Determination of Formate in Natural Waters by a Coupled Enzymatic/High-Performance Liquid Chromatographic Technique

An enzymatic method was developed to quantify formic acid in natural water samples at submicromolar concentrations.The method is based on the oxidation of formate by formate dehydrogenase with corresponding reduction of β-nicotinamide adenine dinucleotide (β-NAD+) to reduced β-NAD+ (β-NADH); β-NADH is quantified by reversed-phase high-performance liquid chromatograhy with fluorometric detection.An important feature of this method is that the enzymatic reaction occurs directly in aqueous media, even seawater, and does not require sample pretreatment other than sample filtration.The reaction proceeds at room temperature at a slightly alkaline pH (7.5-8.5) and is specific for formate with a detection limit of 0.5 μM (S/N = 4) for a 200-μL injection.The precision of the method was 4.6percent relative standard deviation (n = 6) for a 0.6 μM standard addition of formate to Sargasso seawater.Average recoveries of 2 μM additions of formate to seawater, porewater, or rain were 103, 103, and 87percent, respectively.Intercalibration with a Dionex ion chromatographic system showed an excellent agreement of 98percent.Concentrations of formate present in natural samples ranged from 0.2 to 0.8 μM for Biscayne Bay seawater, 0.4 to 10.0 μM for Miami rain, and 0.9 to 8.4 μM for Biscayne Bay sediment porewater.

TENTATIVES DE REGENERATION DU COENZYME NADH PAR REDUCTION ELECTROCHIMIQUE ET HYDROGENATION CATALYTIQUE

Among the various attempts for the electrochemical reduction of NAD(1+) on a platinum electrode only those realized with an electrode submitted to repetitive potentiodynamic perturbations lead to NADH with very low rates.Hydrogenation by molecular hydrogen catalysed by platinum allows the transformation of about 50percent of NAD(1+) in β-NADH enzymatically active.The reaction is faster with platinized platinum.In both cases β-NADH evolves with time to give three non identified products.

Sulfoxylate Ion (HSO2-), the Hydride Donor in Dithionite-Dependent Reduction of NAD+ Analogues

At high pH interaction of dithionite with NAD+ analogues results in formation of a sulfinate adduct.Its rate of formation is linearly dependent on dithionite concentration.Hence, sulfinate radicals do not appear to be involved in this process.A linear free energy relationship for adduct formation is obtained, the rate of which increases with increasing redox potential of the NAD+ analogue.The deproptonated adducts are found to be very stable both thermodynamically (Kd -7 M) and kinetically (koff -4 s-1).Formation of NADH analogues is therefore not observed at pH > 11.Conversion of adducts, formed from stoichiometric amounts of NAD+ analogue and dithionite at high pH, to NADH analogues can be studied by pH jump, stopped-flow spectrophotometry: (1) After protonation of the sulfinate function, formation of oxidized NAD+ analogue is observed in a fast initial phase (k for NAD+ = 4.62 s-1), the rate of which increases with decreasing redox potential of nicotinamide. (2) In a much slower, second phase, formation of NADH analogue is observed, which takes more than 20 min to completion.NADH formation can be prevented by adding formaldehyde, which traps the active reducing species. (3) If NAD sulfinate is mixed at pH 5 with an equimolar amount of the high-potential analogue 3-acetylpyridine-NAD+ almost quantitative formation of 3-acetylpyridine-NADH is observed with no detectable formation of NADH.These results lead us to propose that sulfoxylate ion (HSO2-), a hydride donor formed after heterolytic dissociation of the protonated sulfinate adduct, is the active reducing species.Neither the sulfinate adduct itself nor sulfinate radicals appear to be productive in NADH formation.Hence, dithionite appears to be a selective, ambivalent reducing agent.While flavins are deruced by the homolytic dissociation product, sulfinate radical, nicotinamides are reduced by the heterolytic dissociation product, sulfoxylate ion.The factors controlling the nicotinamide pathway are both the high thermodynamic instability of the nicotinamide radical and the high stability of the sulfinate adduct.