ИСТИНА

D-amino acid oxidase (DAAO, EC 1.4.3.3) is FAD-containing enzyme and catalyses oxidative deamination of D-amino acids to corresponding α ketoacids. The enzyme is widely occured in nature. In mammalian DAAO is responsible in control of level of D-amino acids whish play important role in many processes including relugation of nervous system. Significant change of D amino acids concentrations could results in serious deseases. For example, DAAO is responsible for maintaining the necessary levels of D-serine in different brain tissues. D-serine participates in the regulation of N methyl-D aspartate receptors (NDMA-receptors). It was shown that the dysfunction of NDMA-receptors resulting from the erroneous expression of DAAO gene is one of the possible causes of schizophrenia [1]. Development of sensitive and specific biosensors for certain D-amino acid can be used for early diagnostics of different deseases. Unfortunately, native DAAO show broad substrate specificity and can not be used in such biosensors. We cloned and expressed in E.coli gene of DAAO from yeasts Trigonopsis variabilis (TvDAAO). Rational design approach was used to obtain mutant TvDAAOs with desired substrate specificity. Some mutant enzymes also shown higher thermal stability and higher activity in reaction of cephalosporin C oxidation. This reaction is used for two-step biocatalytic process to prepare 7-amino cephalosporanic acid, a key intermediate for preparation of many semi-synthethic cephalospoins of different generations.