Development of oxidoreductases for amino acid quantification and mutagenesis techniques for heterologous soluble expression: Screening and selection strategies.

The high stereo- and substrate specificities of enzymes have been utilized for micro-determination of amino acids. Here, I review the discovery of L-Arg oxidase from Pseudomonas sp. TPU 7192, L-Lys oxidase/decarboxylase from Burkholderia sp. AIU 395, and enzymes showing apparent L-His oxidase activity from Achromobacter sp. TPU 5009. I also discuss screening and uses of the selective enzymes for micro-determination of amino acids. In addition, functional modifications of L-amino acid oxidase/monooxygenase from Pseudomonas sp. AIU 813, L-Trp dehydrogenase from Nostoc punctiforme ATCC 29133, and L-Lys ε-oxidase from Marinomonas mediterranea NBRC 103028 by directed evolution are reviewed. Finally, I review the rational identification of aggregation hotspots based on secondary structure and amino acid hydrophobicity-this process enables the wider use of natural enzymes.