Prokaryotic Expression and Enzymatic Properties of α-galactosidase from Geobacillus thermodenitrificans

In this study,the gene encoding α-galactosidase from Geobacillus thermodenitrificans was expressed recombinantly using the prokaryotic expression system of Escherichia coli,and the enzymatic properties of the enzyme were studied. The results showed that,the molecular weight of the α-galactosidase was 100~110 kDa. When pNPG was used as the substrate,the optimum reaction temperature of the enzyme was 70 ℃,the optimum pH was 6.0,and the enzyme had good temperature stability and pH stability. Hg⁺,Ag⁺ and Cu²⁺ ions could completely inhibit its enzyme activity,Fe³⁺,Mn²⁺,Zn²⁺ and other ions had different degrees of activation of α-galactosidase activity. The Michaelis constant was measured using pNPG as a substrate,K_m=10.04 mmol/L,the maximum reaction rate V_max=18.25 μmol/min.