title: Thermostable dipeptidase from Bacillus stearothermophilus: its purification, characterization, and comparison with aminoacylase.
abstract: Dipeptidase (dipeptide hydrolase [EC 3.4.13.11]) has been purified to homogeneity and crystallized from the cell extract of Bacillus stearothermophilus IFO 12983. The enzyme has a molecular weight of about 86,000, and is composed of two subunits identical in molecular weight (43,000). The enzyme contains 2 g atoms of zinc per mol of protein. A variety of dipeptides consisting of glycine or only L-amino acids serve as substrates of the enzyme; Km and Vmax values for L-valyl-L-alanine are 0.5 mM and 68.0 units/mg protein, respectively. The enzyme is significantly stable not only at high temperatures but also on treatment with protein denaturants such as urea and guanidine hydrochloride. The enzyme also catalyzes hydrolysis of several N-acylamino acids with Vmax values 3-30% of those for the hydrolysis of dipeptides. The thermostable dipeptidase shares various properties with bacterial aminoacylase [EC 3.5.1.14]: their subunit molecular weight, metal content and requirement, amino acid composition, and amino acid sequence in the N-terminal region are very similar.
mesh_terms: D000581:Amidohydrolases; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid / Q000379:methods; D003460:Crystallization; D004150:Dipeptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D004795:Enzyme Stability; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D005779:Immunodiffusion; D007526:Isoelectric Point; D008670:Metals / Q000032:analysis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D000596:Amino Acids; D008670:Metals; D004150:Dipeptidases; D000581:Amidohydrolases; C019672:aminoacylase I