New Photoproducts from Irradiation of NADH with Near‐UV Light

Vitinius, Ute; Schaffner, Kurt; Demuth, Martin; Heibel, Marija; Selbach, Horst

doi:10.1002/cbdv.200490109

Cited by 10 publications

(15 citation statements)

References 17 publications

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“…This was shown to be true for 1,4‐NADH, as demonstrated by the 1 H NMR spectrum of a standard solution in phosphate buffer after irradiation for ∼12 h by the same UV‐LED used in the photoelectrochemistry experiment. NAD + and minor amounts of ADPR and free nicotinamide were detected, in agreement with findings published by Vitinius et al . UV light was employed in the initial photoelectrochemistry study to excite the direct band gap transition in p ‐GaP (2.3 eV) .…”

Section: Resultssupporting

confidence: 89%

Photoelectrochemical NADH Regeneration using Pt‐Modified p‐GaAs Semiconductor Electrodes

2017

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Cofactor regeneration in enzymatic reductions is crucial for the application of enzymes to both biological and energy-related catalysis. Specifically, regenerating NADH from NAD + is of great interest, and using electrochemistry to achieve this end is considered a promising option. Here, we report the first example of photoelectrochemical NADH regeneration at the illuminated (l > 600 nm), metal-modified, p-type semiconductor electrode Pt/p-GaAs. Although bare p-GaAs electrodes produce only enzymatically inactive NAD 2 , NADH was produced at the illuminated Pt-modified p-GaAs surface. At low overpotential (À0.75 V vs. Ag/AgCl), Pt/p-GaAs exhibited a seven-fold greater faradaic efficiency for the formation of NADH than Pt alone, with reduced competition from the hydrogen evolution reaction. Improved faradaic efficiency and low overpotential suggest the possible utility of Pt/p-GaAs in energy-related NADHdependent enzymatic processes. Scheme 1. Structure of NAD + (nicotinamide) and two-electron redox conversion between NAD + and NADH (1,4-dihydronicotinamide), which occurs in enzymatic processes (ADPR = adenosine diphosphoribose).

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Section: Resultssupporting

confidence: 89%

Photoelectrochemical NADH Regeneration using Pt‐Modified p‐GaAs Semiconductor Electrodes

2017

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“…This absorption peak was significantly reduced after heat treatment at 150 8C. Our observation of an absorbance maximum near 340 nm in the absorption spectrum is consistent with previous reports [35,36] and enabled us to identify NADH with strong adsorption near 340 nm and NAD þ with negligible adsorption. The effect of heat treatment in the SWCNT channel was clearly visible in Figure 2b and c. After a simple drying at 40 8C, the magnitude of I DS was decreased by two orders of magnitude for an applied negative V G compared to the asprepared sample.…”

Section: Resultssupporting

confidence: 80%

Restorable Type Conversion of Carbon Nanotube Transistor Using Pyrolytically Controlled Antioxidizing Photosynthesis Coenzyme

Kang

Kim

et al. 2009

Adv Funct Materials

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Here, a pyrolytically controlled antioxidizing photosynthesis coenzyme, β‐Nicotinamide adenine dinucleotide, reduced dipotassium salt (NADH) for a stable n‐type dopant for carbon nanotube (CNT) transistors is proposed. A strong electron transfer from NADH, mainly nicotinamide, to CNTs takes place during pyrolysis so that not only the type conversion from p‐type to n‐type is realized with 100% of reproducibility but also the on/off ratio of the transistor is significantly improved by increasing on‐current and/or decreasing off‐current. The device was stable up to a few months with negligible current changes under ambient conditions. The n‐type characteristics were completely recovered to an initial doping level after reheat treatment of the device.

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“…This could be due not only to the reduced generation of 1,4-NADH (which has been proved to also contribute to the generation of Ru-H species) [30] but also due to possible simultaneous photodegradation of 1,4-NADH to NAD + upon photoirradiation by UVA (λ irr = 300-400 nm), as it has been recently suggested NAD + is indicated in dark green and 1,4-NADH in red. [31]. It is believed that NAD + , adenosine 5'-diphosphoribose (ADPR) and a second compound, which may be nicotinamide (NA) are the photoproducts resulting from long-time exposures (2 days) of 1,4-NADH to UVA photoirradiation (λ irr = 300-400 nm) in water and normal O 2 levels form the atmosphere.…”

Section: Discussionmentioning

confidence: 99%

Transfer Hydrogenation Reactions of Photoactivatable N,N’-Chelated Ruthenium(II) Arene Complexes

2017

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We show that the reaction of RuII arene chlorido complexes of the type [(η6-arene)Ru(N,N’)Cl]+ arene = p-cymene (pcym), hexamethylbenzene (hmb), indane (ind), N,N’ = bipyrimidine (bpm) and 1,10-phenanthroline (phen) with excess sodium formate generates a very stable formate adduct through spontaneous hydrolysis of the Ru-Cl bond at 310 K and pH* = 7.0. The formate adducts are also produced when RuII arene pyridine complexes of the type [(η6-arene)Ru(N,N’)(Py)]2+ (where Py = pyridine), are irradiated with UVA (λirr = 300-400 nm) or visible light (λirr = 400-660 nm) under the same conditions. The RuII arene formato adducts do not catalyse the reduction of acetone through transfer hydrogenation. However, all the complexes (except complex 2 which contains phen as the chelating ligand) can catalyse the regioselective reduction of NAD+ in the presence of formate (25 mol equiv) in aqueous solution to form 1,4-NADH. The catalytic activity is dependent on the nature of the chelating ligand. Most interestingly, the regioselective reduction of NAD+ to 1,4-NADH can be also specifically triggered by photoactivating a RuII arene Py complex.

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New Photoproducts from Irradiation of NADH with Near‐UV Light

Cited by 10 publications

References 17 publications

Photoelectrochemical NADH Regeneration using Pt‐Modified p‐GaAs Semiconductor Electrodes

Photoelectrochemical NADH Regeneration using Pt‐Modified p‐GaAs Semiconductor Electrodes

Restorable Type Conversion of Carbon Nanotube Transistor Using Pyrolytically Controlled Antioxidizing Photosynthesis Coenzyme

Transfer Hydrogenation Reactions of Photoactivatable N,N’-Chelated Ruthenium(II) Arene Complexes

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