In bacteria, yeast, and fungi, the main role ofthis enzyme is limited to the utilization of exogenous D-amino acids (primarilyD-Ala) [1, 2].In higher eukaryotes – vertebrates and especially inmammals, the main role of DAAO is to maintain a certain level of D-amino acids,which are regulators of many important processes, primarily nervous activity.For example, a decrease in the level of D-Ser in the cerebrospinal fluid due toincreased DAAO activity is associated with schizophrenia[3, 4]. This evidence concerns the gene DAO and schizophrenia.