Mediator-free NADH photochemical regeneration with the aid of the amino acid l-cysteine

Abstract

A strongly photoreducing ruthenium complex has been used to regenerate nicotinamide cofactor with only visible light and L-cysteine. The photoinduced processes have been deeply characterized, and the emission of NADH...

NADH Photoregeneration in a Fully Automated Microfluidic Setup

“…Then, the formation of the desired product was monitored following the 340 nm absorption band and verifying the 470 nm emission signal typical of enzymatically active 1,4-NADH (Figure a). As we described in our previous work, the combination of absorption and emission signal of the produced NADH uniquely identifies the enzymatically active product …”

Photocatalytic Regeneration of a Nicotinamide Adenine Nucleotide Mimic with Water-Soluble Iridium(III) Complexes

“…In biological systems, the regioselective regeneration of the 1,4-NADH isomer from NAD + is orchestrated enzymatically, whereas in artificial settings this is typically achieved with an organometallic rhodium co-catalyst derived from [Cp*Rh­(bpy)­Cl] + , where Cp* = C 5 Me 5 – and bpy = 2,2′-bipyridine. , The catalytically active [Cp*Rh­(bpy)­H] + species can be photochemically generated by the consecutive transfer of two electrons from a sensitizer (Figure ) along with a proton transfer from a suitable source. Such catalytic cycles necessitate robust photosensitizers that can act as very strong electron donors under physiological conditions. , To date, several different types of heterogeneous photocatalysts, − including graphene-based materials, , semiconductors, and Cd-based nanocrystals, have been used for this purpose. , Among homogeneous photocatalysts, derivatives of [Ru­(bpy) 3 ] 2+ , − Zn porphyrins, − or xanthene dyes have been popular. Aside from eosin Y, which can coordinate to the abovementioned rhodium co-catalyst, thus enabling efficient intramolecular electron transfer within the resulting photosensitizer-rhodium dyad, the turnover frequencies (TOF) for both heterogeneous and homogeneous conditions have remained somewhat modest in many cases, with TOF values typically below 20 h –1 at room temperature.…”

“… 1 , 2 To date, several different types of heterogeneous photocatalysts, 21 − 24 including graphene-based materials, 21 , 22 semiconductors, and Cd-based nanocrystals, have been used for this purpose. 23 , 24 Among homogeneous photocatalysts, derivatives of [Ru(bpy) 3 ] 2+ , 25 − 29 Zn porphyrins, 30 − 32 or xanthene dyes 33 have been popular. Aside from eosin Y, which can coordinate to the abovementioned rhodium co-catalyst, 33 thus enabling efficient intramolecular electron transfer within the resulting photosensitizer-rhodium dyad, the turnover frequencies (TOF) for both heterogeneous and homogeneous conditions have remained somewhat modest in many cases, with TOF values typically below 20 h –1 at room temperature.…”

Self-Sufficient Reusable Biocatalytic System Outfitted with Multiple Oxidoreductases and Flexible Polypeptide-Based Cofactor Swing Arms

“…However, cofactors are often much more expensive than the desired products, and therefore, their efficient regeneration becomes critical to sustaining the reaction without the consumption of these expensive cofactors (Figure a) . The chemical, photochemical, , and electrochemical , cofactor regeneration strategies have previously been reported. Enzymatic cascade reactions, including in situ cofactor regeneration, with high reactivity and substrate specificity, have been developed. , In particular, many industrial enzymatic processes use immobilized enzymes to enhance the productivity and thermal/operating stability, tune the selectivity and specificity, and facilitate enzyme purification and product separation. − It is noteworthy that the advantages of immobilization can only be taken if a proper and controllable protocol is utilized .…”

“…16 However, cofactors are often much more expensive than the desired products, and therefore, their efficient regeneration becomes critical to sustaining the reaction without the consumption of these expensive cofactors (Figure 1a). 17 The chemical, 18 photochemical, 19,20 and electrochemical 21,22 cofactor regeneration strategies have previously been reported. Enzymatic cascade reactions, including in situ cofactor regeneration, with high reactivity and substrate specificity, have been developed.…”