A lipase is an enzyme that catalyzes the hydrolysis of fats.
Lipases are a subclass of the esterases.
Lipases perform essential roles in the digestion, transport and processing of dietary lipids
in most, if not all, living organisms.
Genes encoding lipases are even present in certain viruses.
Most lipases act at a specific position on the glycerol backbone of lipid substrate(small
intestine).
For example, human pancreatic lipase, which is the main enzyme that breaks down dietary
fats in the human digestive system, converts triglyceride substrates found in ingested
oils to monoglycerides and two fatty acids.
Several other types of lipase activities exist in nature, such as phospholipases and sphingomyelinases,
however these are usually treated separately from "conventional" lipases.
Some lipases are expressed and secreted by pathogenic organisms during the infection.
In particular, Candida albicans has a large number of different lipases, possibly reflecting
broad lipolytic activity, which may contribute to the persistence and virulence of C. albicans
in human tissue.
Structure and catalytic mechanism Although a diverse array of genetically distinct
lipase enzymes are found in nature, and represent several types of protein folds and catalytic
mechanisms, most are built on an alpha/beta hydrolase fold and employ a chymotrypsin-like
hydrolysis mechanism involving a serine nucleophile, an acid residue, and a histidine.
Physiological distribution Lipases are involved in diverse biological
processes ranging from routine metabolism of dietary triglycerides to cell signaling
and inflammation.
Thus, some lipase activities are confined to specific compartments within cells while
others work in extracellular spaces.
In the example of lysosomal lipase, the enzyme is confined within an organelle called the
lysosome.
Other lipase enzymes, such as pancreatic lipases, are secreted into extracellular spaces where
they serve to process dietary lipids into more simple forms that can be more easily
absorbed and transported throughout the body.
Fungi and bacteria may secrete lipases to facilitate nutrient absorption from the external
medium.
Certain wasp and bee venoms contain phospholipases that enhance the "biological payload" of injury
and inflammation delivered by a sting.
As biological membranes are integral to living cells and are largely composed of phospholipids,
lipases play important roles in cell biology.
Malassezia globosa, a fungus that is thought to be the cause of human dandruff, uses lipase
to break down sebum into oleic acid and increase skin cell production, causing dandruff.
Human lipases The main lipases of the human digestive system
are human pancreatic lipase and pancreatic lipase related protein 2, which are secreted
by the pancreas.
Humans also have several other related enzymes, including hepatic lipase, endothelial lipase,
and lipoprotein lipase.
Not all of these lipases function in the gut.
Other lipases include LIPH, LIPI, LIPJ, LIPK, LIPM, LIPN, MGLL, DAGLA, DAGLB, and CEL.
There also are a diverse array of phospholipases, but these are not always classified with the
other lipases.
Industrial uses Lipases serve important roles in human practices
as ancient as yogurt and cheese fermentation.
However, lipases are also being exploited as cheap and versatile catalysts to degrade
lipids in more modern applications.
For instance, a biotechnology company has brought recombinant lipase enzymes to market
for use in applications such as baking, laundry detergents and even as biocatalysts in alternative
energy strategies to convert vegetable oil into fuel.High enzyme activity lipase can
replace traditional catalyst in processing biodiesel, this enzyme is more environmental
and safe.
Industrial application of lipases requires process intensification for continuous processing
using tools like continuous flow microreactors at small scale.
Lipases are generally animal sourced, but can also be sourced microbially.
Diagnostic use Blood tests for lipase may be used to help
investigate and diagnose acute pancreatitis and other disorders of the pancreas.
Measured serum lipase values may vary depending on the method of analysis.
Additional images
See also Alpha toxin
Lysosomal acid lipase deficiency Peripheral membrane proteins
Phospholipase A Phospholipase C
Triglyceride lipase References
25.
Gulzar, Bio-degradation of hydrocarbons using different bacterial and fungal species.
Published in international conference on biotechnology and neurosciences.
CUSAT, 2004 External links
Lipase at the US National Library of Medicine Medical Subject Headings
Selective Inhibitors of Monoacylglycerol Lipase as a Treatment for Neurological Disorders
2004-637 UMich Orientation of Proteins in Membranes
families/superfamily-90 - Phospholipases A2 UMich Orientation of Proteins in Membranes
families/superfamily-29 - Outer membrane phospholipase A
UMich Orientation of Proteins in Membranes families/superfamily-134 - Cytosolic phospholipase
A2 and patatin UMich Orientation of Proteins in Membranes
families/superfamily-126 - Bacterial and mammalian phospholipases C
UMich Orientation of Proteins in Membranes families/superfamily-88 - α-toxin
Lipase at Lab Tests Online