Rong_2018_Prep.Biochem.Biotechnol_48_113

A novel esterase gene (e25) was identified from Altererythrobacter epoxidivorans CGMCC 1.7731(T) by genome sequence screening. The e25 gene is 948 nucleotides in length and encodes a 315 amino acid protein (E25) with a predicted molecular mass of 33,683 Da. A phylogenetic tree revealed that E25 belongs to the hormone-sensitive lipase (HSL) family of lipolytic enzymes. An activity assay of E25 showed that it exhibited the highest catalytic efficiency when using p-nitrophenyl caproate (C6) as a substrate. The optimum pH and temperature were determined to be approximately pH 9 and 45 degrees C, and the Km and Vmax values were 0.12 mM and 1,772 micromol/min/mg, respectively. After an incubation at 40 degrees C for 80 min, E25 retained 75% of its basal activity. The enzyme exhibited good tolerance to metal cations, such as Ba(2+), Ca(2+), and Cu(2+) (10 mM), but its activity was strongly inhibited by Co(2+), Ni(2+), Mn(2+), and Zn(2+). The E25 enzyme was stimulated by glycerol and retained over 60% of its basal activity in the presence of 1% Tween-80 and Triton X-100. Overall, the activity of E25 under alkaline conditions and its organic solvent and detergent tolerance indicate that E25 could be useful as a novel industrial catalyst in biotechnological applications.