Expression and purification of organic solvent stable lipase from soil metagenomic library

Gene for organic solvent stable lipase was
overexpressed from soil metagenomic library. The clone
with maximum activity was selected, and enzyme was
purified by gel-permeation chromatography with a molecular
mass of approx. 40 kDa. The deduced aminoacid
sequence indicated that the protein belongs to the lipase
family I.3 and containing a C-terminal secretion signal for
ABC dependent transport together with possible motifs for
Ca2 binding sites. The enzyme expressed maximum
activity at 30 C and pH 7.0 and found to be stable in pH
and temperature ranging from 6.0–9.0 and 20–60 C,
respectively. Furthermore, the enzyme was found highly
resistant to many organic solvents, especially isopropanol,
DMSO, methanol, xylene and hexane. The enzyme showed
enhanced activity in the presence of divalent cations
(Mg2, Mn2, Ca2, Hg2, Cu2), whereas the presence of
trivalent cation (Fe3) inhibited the activity.