ИСТИНА

D-amino acids oxidase (DAAO) is the enzyme of high practical interest for nowadays due to the ability to oxidize D-amino acids with absolute stereospecificity. Also it plays variety of important roles in living beings from microorganisms to humans. Currently our laboratory is interested in studying structure-functional relationships of DAAO from the yeast Trigonopsis variabilis (TvDAAO) as well as obtaining mutant forms of the enzyme with improved properties using rational protein design technique. Recently flexible residue of Met104 was found to be located on the entrance of the active site. The Met104 was substituted with small and bulky amino acids (total 10 amino acid changes). The Met104residue was shown to play major role in substrate specificity presumably by controlling substrate binding. Size, shape and charge of introducing residues in position concerned had significant influence on thermal stability, bulky aromatic substitutions stabilizing the enzyme in contrast to the aliphatic amino acids. To figure out the reasons of stabilization effect and interaction with spatially closed residues of Phe54 and Phe258 a series of double mutants was obtained and characterized.