58-68-4Relevant articles and documents
Mechanistic Aspects of the Electrochemical Oxidation of Dihydronicotinamide Adenine Dinucleotide (NADH)
Moiroux, Jacques,Elving, Philip J.
, p. 6533 - 6538 (1980)
The apparently single stage anodic oxidation of NADH involving removal of two electrons and a proton to form NAD+ has been examined with particular attention to the deprotonation step and its relationship to the initial potential-determining electron-transfer step, primarily at glassy carbon electrodes (GCE) in aqueous media with supplementary studies at pyrolytic graphite and platinum electrodes in aqueous media and at GCE in Me2SO; the carbon electrodes were generally first covered with an adsorbed NAD+ layer in order to eliminate adsorption-controlled faradaic processes.The initial step is an irreversible heterogeneous electron transfer (transfer coefficient β = 0.37 at carbon electrodes and 0.43 at platinum).The resulting cation radical NAD.H+ loses a proton (first-order reaction; rate constant k) to form the neutral radical NAD. which may participate in a second heterogeneous electron transfer (ECE mechanism) or in a homogeneous electron transfer with NAD.H+ (disproportionation mechanism DISP 1 or half-regeneration mechanism), yielding NAD+.The near identities of current functions, viscosity-corrected diffusion coefficients D and β values, point to essentially similar solute species and charge-transfer paths being involved in different media and at different electrodes.D is ca. 2 x 10-6 cm2 s-1 in aqueous solution; k is ca. 60 s-1 at the GCE covered with adsorbed NAD+.
A highly active Cp*Ir complex with an anionic N,N-donor chelate ligand catalyzes the robust regeneration of NADH under physiological conditions
Qi, Caixia,Shi, Yusheng,Su, Huijuan,Sun, Libo,Sun, Wen,Sun, Xun,Xia, Linyan,Yin, Zequn,Zhang, Weiling,Zhao, Li-Jun
, p. 7982 - 7991 (2021/12/27)
A highly active [N^N?] iridium complex [Cp*Ir(pba)Cl] (3, Cp* = pentamethylcyclopentadiene, pba = 4-(picolinamido)benzoic acid) has been obtained with an anionic ligand, which exhibited the most robust performance for cofactor NADH regeneration in physiological conditions with HCOONa as the hydrogen source. The structure of complex3was revealed by X-ray single-crystal structure analysis. The turnover frequency (TOF) of complex3in the regeneration of NADH is 7825 h?1, which is about 22.7 times and 178 times higher than that of the C?^N type complex2(345 h?1) and N^N complex1(44 h?1) at 37 °C, respectively. The high activity of complex3seems to be critically affected by the negatively charged N?of the amide chelating ligand, which could promote the reaction rate of Ir-Cl conversion to Ir-H2O. Furthermore, complex3shows good biocompatibility for various biomolecules except SH-compounds (such as reduced glutathione (GSH)). When combined with NADH-dependent enzymes (KRED-101), the complex3-based NADH-regeneration catalytic system shows stable chemoenzymatical coordinate catalytic activity for reducing acetophenone to the corresponding alcohol with high enantioselectivity.
Chemo-bio catalysis using carbon supports: application in H2-driven cofactor recycling
Cleary, Sarah E.,Grobert, Nicole,Reeve, Holly A.,Vincent, Kylie A.,Zhao, Xu,Zor, Ceren
, p. 8105 - 8114 (2021/06/22)
Heterogeneous biocatalytic hydrogenation is an attractive strategy for clean, enantioselective CX reduction. This approach relies on enzymes powered by H2-driven NADH recycling. Commercially available carbon-supported metal (metal/C) catalysts are investigated here for direct H2-driven NAD+reduction. Selected metal/C catalysts are then used for H2oxidation with electrons transferredviathe conductive carbon support material to an adsorbed enzyme for NAD+reduction. These chemo-bio catalysts show improved activity and selectivity for generating bioactive NADH under ambient reaction conditions compared to metal/C catalysts. The metal/C catalysts and carbon support materials (all activated carbon or carbon black) are characterised to probe which properties potentially influence catalyst activity. The optimised chemo-bio catalysts are then used to supply NADH to an alcohol dehydrogenase for enantioselective (>99% ee) ketone reductions, leading to high cofactor turnover numbers and Pd and NAD+reductase activities of 441 h?1and 2347 h?1, respectively. This method demonstrates a new way of combining chemo- and biocatalysis on carbon supports, highlighted here for selective hydrogenation reactions.
