Physiological Role of D-amino Acids and Bioanalytical Potential of D-amino Acid Oxidases

Abstract

D-amino acid oxidase (DAAO) plays an important role in the functioning of both prokaryotes and eukaryotes. DAAO is increasingly being used in practice, including for the determination of D-amino acids in complex samples, involving human tissues and fluids. There are generally two types of DAAO in all organisms. The first type is an enzyme highly specific for D-aspartate and has its own name D-aspartate oxidase (DASPO). DAAO of the second type is characterized by a wide spectrum of substrate specificity, with preference for one or another D-amino acid varying from source to source. The activity of DAAO with a large number of substrates greatly complicates the selective determination of a particular D-amino acid. The problem is often solved by choosing an enzyme that, under the conditions of analysis, has low or no activity with other D-amino acids present in the sample. For the convenience of selecting a particular enzyme, we have collected and analyzed literature data on the catalytic parameters of known DAAOs with the most important D-amino acids. In addition, similar data are presented for novel recombinant DAAOs from the methylotrophic yeast Ogataea parapolymorpha DL-1. Analysis of the data shows that, with the D-amino acid series, the new OpaDASPO and OpaDAAO have the highest catalytic parameters.