[Purification, characterization and substrate selectivity analysis of transaminase from marine actinomycetes]

This study addresses the demand for green biosynthesis of chiral amine drugs by developing a novel R-selective amine transaminase (PamAT) derived from the marine actinomycete Pseudonocardia ammonioxydans. Following recombinant expression in Escherichia coli and purification via nickel-affinity chromatography, PamAT exhibited remarkable catalytic properties: strict stereoselectivity; a broad substrate spectrum; enhanced solvent tolerance (retaining>80% activity in 10% methanol or acetonitrile). Enzyme activity assays revealed that PamAT achieved the activity of (7.57±0.42) U/mg under mild conditions. Molecular docking and structural simulations elucidated the substrate recognition mechanism and key amino acid residues controlling stereoselectivity. The results indicate that PamAT holds significant potential for industrial applications, offering not only a new tool for the green synthesis of chiral amine drugs but also novel insights for the development of marine microbial enzymes.