ИСТИНА

D-amino acid oxidase (DAAO) is used in process of 7-aminocephalosporanic acid from Cephalosporin C. The enzyme from yeast Trigonopsis variabilis (TvDAAO) shows the highest activity with Cephalosporin C. We cloned and expressed in E. coli cells gene of TvDAAO. recombinant TvDAAO was purified and characterized. Native TvDAAO is dimer. It was found that TvDAAO activity depends on enzyme concentration. Study of thermal stability showed that at concentrations lower than 40 μg/ml enzyme inactivation kinetics is described with two-exponential function. At higher concentrations inactivation kinetics is more complicated. In initial stage there is increase of enzyme activity followed by two-exponential kinetics. Scheme of enzyme inactivation was proposed. It includes production of oligomers higher than dimer at concentrations above 40 μg/ml and reversible dissociation of dimer to subunits which than irreversibly denaturated. Oligomers higher than dimer are inactive and activation of TvDAAO at high concentrations in initial stage of thermal inactivation is result high oligomers dissociation to dimer. This work was supported by Russian Science Foundation (project 16-04-00043)