Abstract
A thermostable lipase, Itb1.1, was previously cloned and expressed. This study was focused on the functional and structural characterization of the enzyme. The functional characterization was performed through hydrolytic and transesterification activity on p-nitrophenyl ester, with decanoate and myristate as preferred substrates. Meanwhile, structural analysis was characterized by in silico and immobilization. The substrates preferences were confirmed by docking analysis. Itb1.1 is a class of thermostable alkaline lipase with optimum hydrolytic activity at 85 oC, pH 9.5. The activity of the enzyme was higher on less polar solvents and increased by the presence of Ca2+ Mg2+, Ni2+ and Fe2+. In contrast on the presence of Mn2+, Cu2+, Co2+, and Zn2+ decreased up to 60 – 40% respectively. The effect of metal ions on the activity of the enzyme might due to changing on the conformation and orientation of catalytic triad. Itb1.1 was stable in non-ionic surfactant and suggest as metalloenzyme and serine hydrolase group. Immobilization on IM-CLPCMC maintained specific activity and prolong stability and reusability of the enzyme. The opposite response on the presence of metal ions to the activity of Itb1.1 compared to that of the lipase of family I.5 suggests that the enzyme might new member of lipase family I.5.