Which organ synthesises lipase

Lipids are a general term for fats and lipoids and their derivatives Figure 1. Fat is triglyceride, also known as triacylglycerol TG ; lipoids include phospholipids PL , glycolipids; cholesterol Ch includes free cholesterol FC and cholesterol ester CE.

The lipids present in various tissues are body fats, and the body fat stores huge energy. When the body heat is insufficient, body fat can be used for energy consumption.

A small number of lipids present in the blood circulation are blood lipids which are mainly phospholipids, triglycerides, cholesterol, free fatty acids, and trace amounts of fat-soluble vitamins and steroid hormones. Free fatty acids are mainly decomposed by TG in body fat and then enter the blood circulation.

Lipids are insoluble in water, and lipids in plasma can only be transported to the body throughout the blood cycle by binding to proteins and becoming hydrophilic.

Free fatty acids bind to albumin while the remaining lipids combine with globulin to form lipoproteins. Lipoproteins containing more TG are with low density, and those containing less TG have higher density. According to the density of lipoproteins, plasma lipoproteins can be divided into four categories: 1 chylomicrons CM ; 2 very low density lipoprotein VLDL ; 3 low density lipoprotein LDL ; 4 high density lipoprotein HDL.

After binding to lipids, proteins take part in transporting lipids in plasma, so they are called apolipoproteins. The mainly lipid source of the liver is food. In the small intestine, bile acids and pancreatic enzymes including pancreatic lipase, phospholipase A2, cholesterol esterase, etc. Other pancreatic enzymes include amylase, which breaks down a certain starch into its sugar building blocks, and protease, which breaks down protein into single amino acids.

Most people do not need additional lipase. However, people with the following conditions may find lipase supplements helpful. Celiac disease is a condition in which gluten a protein found in grains damages the intestinal tract. Symptoms include abdominal pain, bloating, weight loss, and fatigue. People with celiac disease must follow a strict diet that is free of gluten. Pancreatic enzymes have been studied as part of the treatment for celiac disease, however, it is not clear how much they help.

In one study of 40 children with celiac disease, for example, those who received pancreatic enzyme therapy including lipase , had a modest weight gain compared to those who received placebo. The weight gain happened during the first month.

Taking pancreatic enzyme supplements for another month did not lead to more weight gain. In a small clinical study of 18 people, supplements containing lipase and other pancreatic enzymes helped reduce bloating, gas, and fullness following a high-fat meal. These symptoms are commonly associated with irritable bowel syndrome IBS. So some researchers speculate that pancreatic enzymes might help treat symptoms of IBS.

No studies have been done to test this theory. People with cystic fibrosis, an inherited condition that causes the body to produce abnormally thick, sticky mucus, often have nutritional deficiencies because mucus blocks pancreatic enzymes from getting to the intestines.

Taking pancreatic enzymes as prescribed by a doctor helps improve the nutrition they get from food. Lipase supplements are usually derived from animal enzymes, although plant sources have become increasingly popular.

Lipase may be taken in combination with protease and amylase enzymes. These pancreatic enzymes are available in tablet and capsule form. Side effects may include nausea and stomach upset. High doses of lipase may exacerbate symptoms of cystic fibrosis. In the bile, among the other components, there are bile salts , phospholipids, and cholesterol. Bile salts are bile acids conjugated with glycine or taurine.

In turn, bile acids are oxygenated derivatives of cholesterol. Bile acids and bile salts are both synthesized by the liver. They are amphipathic molecules, in whose planar ring structure you can identify a hydrophobic face and a hydrophilic face. Therefore, they are able to further emulsify lipid droplets, increasing the surface area for hydrolase activity.

In particular, salts of cholic acid, which contain three hydroxyl groups, are better emulsifiers than salts of deoxycholic acid, which instead contain only two hydroxyl groups. Note: the gallbladder secretes about 30 g of bile salts each day, together with phospholipids and cholesterol. Most of the bile salts and cholesterol is then reabsorbed, so that the daily fecal loss of bile salts and steroids is quite low, 0.

The mechanism of peristalsis and the surfactants seen so far free fatty acids, acylglycerols, phospholipids, and bile salts ensure the formation of microscopic micelles, which further increase the available surface areas for hydrolytic enzyme activities.

It should be underlined that triacylglycerols with short-chain and medium-chain fatty acids can be both hydrolyzed and absorbed in the absence of bile salts, although their presence increases the absorption. Cholecystokinin also stimulates the exocrine pancreas to secrete a pancreatic juice containing, among other molecules, pancreatic lipase.

The enzyme catalyzes the digestion of the majority of ingested triglycerides, mainly in the upper portion of the jejunum, and has a optimum pH of 7. It catalyzes the cleavage of fatty acids, typically with 10 or more carbon atoms, primarily in sn -1 and sn -3 positions of the glycerol backbone.

The products of the reaction are free fatty acids and 2-monoacylglycerols. The 2-monoacylglycerol, the main form in which the monoacylglycerols are absorbed from the small intestine, can undergo an isomerization process in which the remaining fatty acid moves to carbon 1 or 3. However, the rate of isomerization is slower than the rate of uptake of the molecule from the small intestine. In vitro , pancreatic lipase is inhibited by bile salts, whereas in vivo , it hydrolyzes triglycerides in a very efficient manner, due to the presence of a protein cofactor secreted by exocrine pancreas, the colipase.

This protein has no catalytic activity, is produced in inactive form, called procolipase, and is activated by trypsin in the duodenum. Lipid droplets are coated with phospholipids and bile salts, that give them a negative charge which prevents the binding of lipase, but attracts the colipase. In turn, colipase binds pancreatic lipase lipase and colipase bind in a molar ratio , thus anchoring the enzyme to the water-lipid interface of the lipid droplets.

This lipase has a neutral pH optimum, and is stimulated by bile salts. The enzyme contributes substantially to hydrolysis of the triglycerides in the intestine of breast-fed infants. Another enzyme present in the pancreatic juice is cholesterol esterase EC 3. The enzyme, synthesized and secreted in an active form by the exocrine pancreas, is a lipase with broad specificity, being active on:. Like phospholipase A 2 see below , it is primarily active on cholesterol esters incorporated into bile salt micelles.

Unlike pancreatic lipase, its activity is stimulated by bile salts, mainly trihydroxy salts, such as sodium taurocholate and glycocholate. These salts induce a protein conformational change that activates the enzyme. Moreover, trihydroxy salts promote its self-association into polymeric aggregates, which protect it from the action of proteases in the intestinal lumen.

The digestion of phospholipids is carried out by phospholipases, primarily phospholipase A 2 EC 3.