Food Lipids: Chemistry, Nutrition, and Biotechnology

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Microbial Lipases
JOHN D. WEETE
West Virginia University, Morgantown, West Virginia
I. INTRODUCTION
Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) are enzymes that catalyze the
reversible hydrolysis of triacylglycerols under natural conditions. Widely distributed
in animals, plants, and microbes, lipases differ from other esterases and are unique
in that their activity is greatest against water-insoluble substrates and is enhanced at
the substrate (oil)–water interface; that is, they exhibit ‘‘interfacial activation.’’ Optimum
activities are obtained in systems such as emulsions, where high surface areas
of the substrate can be obtained. Lipases are active not only in normal phase emulsions
where the substrate is emulsified into an aqueous system (oil-in-water), but
they are also active, often more active, in invert (water-in-oil) emulsions and in
reverse micelle systems containing an organic solvent solution of the substrate. Furthermore,
lipases are exceedingly versatile in that they can also catalyze transesterification
reactions and the stereospecific synthesis of esters, and they can act on a
broad range of substrates.
Major advances have been made in our understanding of lipolytic enzymes
over the past few years through solving the crystal structures of lipases from several
sources. Knowledge of their structures has given insight into the mechanism of action,
interfacial activation, specificity, and the nature of the active site. The high
current interest in lipases, shown by the large volume of recent scientific literature
on the topic, is driven by the great potential in a diversity of commercial applications
for these enzymes. This chapter gives an overview of lipases and their properties,
with a focus on the topics of current research interest such as lipase structure and
its implications in interfacial activation and selectivity. The emphasis is on microbial
lipases, particularly from fungi, with references to human pancreatic lipase for
comparison.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.