REVIEW: D-Amino Acid Transaminases: Structural Diversity, Catalytic Properties, and Potential Applications

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Alina K. Bakunova¹, Sofia A. Shilova¹, Vladimir O. Popov^1,2, and Ekaterina Yu. Bezsudnova^1,a*

¹Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology”, Russian Academy of Sciences, 119071 Moscow, Russia

²Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia

^* To whom correspondence should be addressed.

Received: April 16, 2025; Revised: May 28, 2025; Accepted: August 12, 2025

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Pyridoxal-5′-phosphate (PLP)-dependent D-amino acid transaminases (DATAs) catalyze stereoselective transfer of an amino group from a D-amino acid to an α-keto acid to form new D-amino acid and α-keto acid. These enzymes are found in bacteria and plants; they are responsible for the synthesis of D-amino acids and are incorporated into the nitrogen cycle. In general, the mechanism of D-transamination is similar to the known mechanism of transamination for aspartate aminotransferase: D-transamination reaction consists of two half-reactions with intermediate transfer of the amino group to the cofactor and formation of its reduced form, pyridoxamine-5′-phosphate. DATAs are characterized by broad substrate specificity and an open active site, which, however, does not affect their high stereoselectivity: no side L-products is detected in the DATA-catalyzed D-transamination. As in other PLP-dependent fold type IV transaminases, the functional unit of DATAs is a dimer. The active site is formed by amino acid residues of both subunits and binding of α-carboxylate group is crucial for proper substrate coordination. DATAs with promiscuous activity towards substrates without an α-carboxylate group, primary (R)-amines, have also been discovered and characterized. The promiscuous activity is achieved through the mobility of certain residues in the active site of DATAs. High stereoselectivity and stability of DATAs make then promising candidates for multienzyme cascade processes as biocatalysts of the (R)-stereoselective amination stage. Open configuration of active site makes binding and conversion of bulk non-natural substrates possible. The review describes in detail properties, structure, and relationships of DATAs from two currently known groups differing in organization of their active sites. The prospects for biotechnological applications of DATAs are discussed as well.

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KEY WORDS: D-amino acid transaminase (DATA), transaminase, pyridoxal-5′-phosphate-dependent catalysis, substrate specificity, three-dimensional structure, structure–function relationship, enzyme stability, biocatalysis, D-stereoselective amination

DOI: 10.1134/S0006297925603247

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