ABSTRACT
Acknowledgments .............................................................................................................. 175
References .......................................................................................................................... 175
Lipases and esterases are, undoubtedly, enzymes with great biotechnological importance.
Approximately 55% of all enzymes used in biocatalysis are hydrolases, lipases (~30%), and
esterases (~8%) being the most predominant enzymes besides proteases, nitrilases, and others
[1,2]. Both of these enzymes belong to the structural superfamily of a/b-hydrolases. This family groups several hydrolytic enzymes of widely differing phylogenetic origin and catalytic
function. The common structural motif comprises eight beta-sheets connected by alpha-
helices. These enzymes seem to diverge from a common ancestor in order to preserve the
160 Biocatalysis in the Pharmaceutical and Biotechnology Industries
arrangement of the catalytic residues. They all have a catalytic triad, the elements of which are
borne on loops, which are the best-conserved structural features in the fold. Only the histidine
in the nucleophile-histidine-acid catalytic triad is completely conserved. In the case of lipases
and esterases the catalytic triad is composed of Ser-Asp-His (Ser-Glu-His for some lipases),
the Ser residue being in the consensus sequence Gly-X-Ser-X-Gly. The unique topological and
sequential arrangement of the triad residues produces a catalytic triad which is, in a sense, a
mirror image of the serine protease catalytic triad [3].
