Enzymatic Characterization of Aminoacylase from Thermophilic Bacteria and Its Application to Amino Acid Production

点击翻译按钮获取中文摘要

This study was undertaken to establish a new rate assay method of aminoacylase, to elucidate enzymological properties of thermostable aminoacylase from thermophilic bacteria to compare with other thermolabile enzymes, and to develop a new enzymatic procedure for the synthesis of amino acids from racemates with the thermostable aminoacylase. The results are summarized as follows:1. A convenient spectrophotometric rate assay for aminoacylase was developped based on the observation that acetamidoacrylate, a synthetic N-acetyl unsaturated amino acid, was hydrolyzed to acetate, ammonia and pyruvate by hog kidney, fungal and bacterial aminoacylases. This assay is linear with time and enzyme concentration, and is useful for kinetic studies of aminoacylase.2. The thermostable aminoacylase was purified to homogeneity from cell extracts of Bacillus thermoglucosidius and characterized. The enzyme has a molecular weight of about 175,000, and is composed of four identical subunits, containing 4 g atoms of zinc per mole of enzyme protein. Great stability at high temperatures and with organic solvents and protein denaturants is a characteristic of the enzyme.3. Enzymological properties of the thermostable dipeptidase from B. stearothermophilus were compared with those of aminoacylase.4. A new enzymatic method for L-phenylalanine production was established.