Database-driven in silico-identification and characterization of novel aldoxime dehydratases

Kinetic model of asymmetric dehydration of aldoxime catalyzed by immobilized OxdPsp in an organic solvent

“…The proposed mechanism for the biotransformation of 1 into 2 via dehydration catalyzed by IOP is shown in Scheme 2 and the enzymatic dehydration course is briefly described as follows. For reaction (1), firstly, substrate (E)-1 enters the active site of OxdPsp (E) and binds E to yield binary complex E(E)-1, where the N-atom of the aldoxime (E)-1 interacts with the Fe II atom of OxdPsp. The fixation of (E)-1 is enhanced due to hydrogen bonds between the OH-group of (E)-1 and the amino acid residue of OxdPsp, and the electrophilicity of the OHgroup of (E)-1 is increased due to the protonation of the histidine residue.…”

“…After the third recycling step of IOP, the yield of (S)-2 was 83.6% (Table 3), indicating a significant improvement in the stability of IOP compared to that of Oxds 12,15 in which all novel Oxds, such as OxdHsp, OxdPsp, OxdHR, OxdB and OxdRE, exhibited low stability and were not capable of affording reuse in organic solvents with lg P < 3. This should be attributed to the use of an organic solvent with lg P > 3, heptane, as the reaction solvent and employing an ATPS coupled with in situ immobilization with an MAR as the carrier in the immobilization of OxdPsp, which are all beneficial for the stability of IOP.…”

“…Organic nitriles are some of the most versatile building blocks and are widely used as chemical raw materials and synthetic intermediates to other valuable functionalized compounds, such as pharmaceuticals, pesticides, fragrances, dyes, polymers, liquid crystal materials, and solvents. 1,2 Currently, the synthesis of nitriles includes bulk chemicals such as acrylonitrile and adiponitrile and fine chemicals with important functions, especially as pharmaceuticals. More than 30 nitrile-containing drugs are used for different conditions, such as cimetidine for heartburn and peptic ulcer, anastrozole for breast cancer, clopidogrel for coronary artery disease, etc.…”

“…Subsequently, the groups of Asano and Gröger 10,11 constructed more than 40 recombinant Oxds from various microorganisms, with a wide range of substrates including aromatic and aliphatic aldoximes. In 2023, Gröger's group 12 constructed 16 novel recombinant Oxds from various microorganisms, namely OxdHsp (Hydrogenophaga sp. RAC07), OxdPsp (Pseudomonas sp.…”

“…For instance, almost no conversion was observed for several free Oxd enzymes and whole cells in organic solvents. 15 Due to the poor stability of Oxds in phosphate buffer and phosphate buffer-organic solvent biphasic reaction media, 10,12,15 organic solvents with a high lg P value may be considered as the reaction media to enhance the stability of the Oxds. For organic solvents with a high lg P, immobilized enzymes must be used, as free enzymes or whole cells are insoluble in organic solvents and are precipitated as pellets with poor dispersion, making them not capable of catalyzing the dehydration of aldoximes.…”