Sequencing and characterization of dual-domain β-propeller alkaline phytase

Abstract:

[Objective] The aim of this study was to purify and characterize a dual-domain β-propeller alkaline phytase (phyHT) from Bacillus sp. HJB17 and to analyze the sequence features for application of the enzyme.[Methods] The amino acid sequence of phyHT was analyzed by bioinformatics methods. PhyHT protein was expressed, refolded, purified and the enzymatic properties were determined by ferrous sulfate and molybdenum blue method.[Results] Sequence analysis suggested that phyHT consisted of 633 amino acids and contained 2 phytase domain and belonged to typical BPP phytase. PhyHT was a hydrophilic protein and the molecular weight and theoretical isoelectric point were 69321.68 Da and 5.37, respectively. In the secondary structure, phyHT mainly consists of α-helix and β-sheet. Its three-dimensional structure mainly consists of β-sheet propeller. The optimum temperature of phyHT was 37℃, and stable at 45℃. PhyHT has an optimum pH of 8.0, and stable between pH 6.0 and 12.0. Low concentration of Ca²⁺ and Mg²⁺ promoted the enzymatic activity, whereas phytase activity was strongly inhibited by Fe²⁺, Mn²⁺, Zn²⁺, Cu²⁺ and Ni²⁺.[Conclusion] phyHT has important applications in theoretical research and in industry.