Kinetics of Thermoinactivation of D-Amino Acid Oxidase OPADAAO1 from the Ogataea parapolymorpha DL-1 Yeast

Our earlier annotation of the genome of the yeast Ogataea parapolymorpha DL-1 made it possible to identify five genes of potential D-amino acids oxidases. All opadaao1–opadaao5 genes were cloned and expressed in E. coli. Four OpaDAAO1-OpaDAAO4 enzymes were obtained in highly purified form and their catalytic properties were studied. It was found that among all DAAO described in the literature, the enzyme OpaDAAOl has the highest catalytic constant k_cat with D-Ala, which makes it promising for practical applications. However, in addition to good catalytic parameters, effective application of the enzyme in practice requires stability and knowledge of the inactivation mechanism, including at elevated temperatures. In this paper, we study the effect of elevated temperatures on the stability of OpaDAAOl. The enzyme is shown to have higher thermal stability than the majority of other D-amino acid oxidases. The kinetics of OpaDAAOl inactivation at different temperatures, at the initial concentrations of the enzyme, and in the presence of exogenous FAD are studied. A possible kinetic scheme of inactivation is proposed based on the data obtained.