What are the building blocks of Lipases?
Last Updated on March 8, 2020 by arkadmin
What is Lipase?
Lipases are enzymes involved in fat digestion. The body includes many subtypes of enzymes, but the term “lipase” usually refers to pancreas lipase. The pancreas is an organ that is located below your stomach. Its role is to break down specific components of dietary fat. Lipase is secreted from the pancreas through a tube that empties into the gastrointestinal tract of the duodenum. Therefore, it acts on the already partially digested food in the stomach.
Lipase, any of a group of fat-splitting enzymes found in the blood, gastric juices, pancreatic secretions, intestinal juices, and adipose tissues. Lipases hydrolyze triglycerides (fats) into their component fatty acid and glycerol molecules.
Initial lipase digestion occurs in the lumen (interior) of the small intestine. Bile salts reduce the surface tension of the fat droplets so that the lipases can attack the triglyceride molecules. The fatty acid and glycerol molecules are then taken up into the epithelial cells that line the intestinal wall, where they are resynthesized into triglycerides for transport to muscles and adipose tissues. At these sites lipases in the bloodstream hydrolyze the triglycerides, and the resulting fatty acids and glycerol are taken up by the cells of these tissues. In the adipose tissues triglycerides are re-formed for storage until the energy needs of the animal increase under conditions of stress or exercise. Lipases in the cells of adipose tissues break down the triglycerides so that fatty acids can reenter the bloodstream for transport to energy-requiring tissues.#
Building Blocks of Lipases-Glycerol and Fats
Lipase is an enzyme that breaks down triglycerides into free fatty acids and glycerol. Lipases are present in pancreatic secretions and are responsible for fat digestion. Lipases are enzymes that play a crucial role in lipid transport. There are many different types of lipases; hepatic lipases are in the liver, hormone-sensitive lipases are in adipocytes, lipoprotein lipase is in the vascular endothelial surface, and pancreatic lipase is in the small intestine, each serving individual functions. Hepatic lipase in the liver is responsible for degrading the triglycerides that remain in intermediate density lipoprotein (IDL). Hormone-sensitive lipase is found within fat tissue and is responsible for degrading the triglycerides that are stored within adipocytes. Lipoprotein lipase is found on the vascular endothelial surface and is responsible for degrading triglycerides that circulating from chylomicrons and VLDLs. Pancreatic lipase is found within the small intestine and is responsible for degrading dietary triglycerides.
Hepatic lipase plays a crucial role in the formation and delivery of low-density lipoprotein(LDL). LDL is formed by the modification of intermediate density lipoprotein in the peripheral tissue and liver by hepatic lipase. These LDL particles are taken up, or endocytosed, via receptor-mediated endocytosis by target cell tissue. LDL serves to ultimately transport cholesterol from the liver to peripheral tissue.
A lipase is any enzyme that catalyzes the hydrolysis of fats (lipids).
Lipases perform essential roles in digestion, transport and processing of dietary lipids (e.g. triglycerides, fats, oils) 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 a lipid substrate (A1, A2 or A3)(small intestine). For example, human pancreatic lipase (HPL), 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 an infection. In particular, Candida albicans has many different lipases, possibly reflecting broad-lipolytic activity, which may contribute to the persistence and virulence of C. albicans in human tissue.
A diverse array of genetically distinct lipase enzymes are found in nature, and they represent several types of protein folds and catalytic mechanisms. However, most are built on an alpha/beta hydrolase fold and employ a chymotrypsin-like hydrolysis mechanism using a catalytic triad consisting of a serine nucleophile, a histidine base, and an acid residue, usually aspartic acid
Lipase in Human Body
The main lipases of the human digestive system are pancreatic lipase (PL) and pancreatic lipase related protein 2 (PLRP2), which are secreted by the pancreas. Humans also have several related enzymes, including hepatic lipase, endothelial lipase, and lipoprotein lipase.
|bile salt-dependent lipase||bsdl||pancreas, breast milk||aids in the digestion of fats|
|pancreatic lipase||PNLIP||digestive juice||In order to exhibit optimal enzyme activity in the gut lumen, PL requires another protein, colipase, which is also secreted by the pancreas.|
|lysosomal lipase||LIPA||interior space of organelle: lysosome||Also referred to as lysosomal acid lipase (LAL or LIPA) or acid cholesteryl ester hydrolase||Cholesteryl ester storage disease (CESD) and Wolman disease are both caused by mutations in the gene encoding lysosomal lipase.|
|hepatic lipase||LIPC||endothelium||Hepatic lipase acts on the remaining lipids carried on lipoproteins in the blood to regenerate LDL (low density lipoprotein).||–|
|lipoprotein lipase||LPL or “LIPD”||endothelium||Lipoprotein lipase functions in the blood to act on triacylglycerides carried on VLDL (very low density lipoprotein) so that cells can take up the freed fatty acids.||Lipoprotein lipase deficiency is caused by mutations in the gene encoding lipoprotein lipase.|
|gastric lipase||LIPF||digestive juice||Functions in the infant at a near-neutral pH to aid in the digestion of lipids||–|
|pancreatic lipase related protein 2||PNLIPRP2 or “PLRP2” –||digestive juice||–||–|
|pancreatic lipase related protein 1||PNLIPRP1 or “PLRP1”||digestive juice||Pancreatic lipase related protein 1 is very similar to PLRP2 and PL by amino acid sequence (all three genes probably arose via gene duplication of a single ancestral pancreatic lipase gene). However, PLRP1 is devoid of detectable lipase activity and its function remains unknown, even though it is conserved in other mammals.||–|
|lingual lipase||?||saliva||Active at gastric pH levels. Optimum pH is about 3.5-6. Secreted by several of the salivary glands (Ebner’s glands at the back of the tongue (lingua), the sublingual glands, and the parotid glands)||–|
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.
Uses of Lipase
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, as this enzyme replaces chemicals in a process which is otherwise highly energy intensive, and can be more environmentally friendly 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.
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.Lipase can also assist in the breakdown of fats into lipids in those undergoing pancreatic enzyme replacement therapy (PERT). It is a key component in Sollpura (Liprotamase).