Characterization of a thermostable arginase from Rummeliibacillus pycnus SK31.001

Publication date: Available online 22 November 2016 Source:Journal of Molecular Catalysis B: Enzymatic Author(s): Kai Huang, Tao Zhang, Bo Jiang, Wanmeng Mu, Ming Miao L-arginase from Rummeliibacillus pycnus SK31.001 is newly discovered. A 906bp complete open reading frame, which encodes a 301 amino acid protein, was identified using degenerate PCR and inverse PCR techniques. The arginase was found to have a conserved active site with 6 amino acid residues binding to 2 manganese ions: D123, H125, D228, D230, H100 and D127. Bioinformatics analysis revealed that R. pycnus arginase is a hexamer with a subunit molecular mass of 33kDa and whole molecular mass of 195kDa. R. pycnus arginase is thermostable with an optimal temperature of 80°C and maintains 85% of its initial activity after 24h of incubation at 40 or 50°C. An arginase activity assay showed that R. pycnus arginase has an optimum pH of 9.5 and a preference for Mn2+. Using arginine as the substrate, the Michaelis-Menten constant (K m) and catalytic efficiency (k cat/K m) were measured to be 0.212mM and 2970mM−1s−1, respectively. The biosynthesis yield of L-ornithine by the purified enzyme was 144.4g/L, and the molar yield was 95.2%. Graphical abstract

Source: Journal of Molecular Catalysis B: Enzymatic - November 21, 2016 Category: Biochemistry Source Type: research