Acta Naturae. 2026 Jan-Mar;18(1):83-90. doi: 10.32607/actanaturae.27820.

ABSTRACT

Pyridoxal-5′-phosphate (PLP)-dependent transaminases are highly efficient biocatalysts for the stereoselective synthesis of chiral amines, which are key building blocks in pharmaceuticals and chemical manufacturing. Fundamental research on enzymatic transamination includes the classical works of Alexander Braunstein, who discovered the transamination reaction; David Metzler, who studied the spectral properties of PLP-dependent enzymes; Esmond Snell, who investigated the kinetics of PLP-dependent enzymes; as well as studies by other Russian and international researchers. Despite extensive studies on PLP-dependent transaminases, their practical application remains limited. In addition to the unfavorable equilibrium of the transamination reaction and the narrow substrate specificity of transaminases, their stability under manufacturing conditions is a major constraint. Transaminase stability encompasses not only the structural integrity of the protein globule, but also the enzyme’s ability to retain the PLP cofactor. PLP dissociation leads to enzyme inactivation and termination of the reaction. Modern biocatalytic processes are predominantly designed for aqueous-organic media to increase the solubility of hydrophobic substrates to hundreds of grams per liter. Under these conditions, the stability of transaminases, as with other enzymes, decreases. In the context of these challenges, this work investigates the efficiency of PLP binding as a factor in stabilizing the active holoenzyme of the transaminase from Desulfomonile tiedjei in various aqueous-organic media. The study analyzes the transaminase stability and catalytic activity in the presence of methanol, DMSO, and Cyrene (up to 20% v/v), both in incubation mode and under reaction conditions. Particular attention is paid to the analysis of the effect of the amino acid substitution T199Q in the cofactor-binding region on the enzyme’s resistance to organic solvents. The present study contributes to addressing the practical problem of stabilizing transaminases in aqueous-organic media. The results also deepen our understanding of the molecular basis of the stability of PLP-dependent enzymes.

PMID:42083597 | PMC:PMC13135825 | DOI:10.32607/actanaturae.27820