Pancreatic lipase lipid digestion

Fats and other lipids are poorly soluble in water. The larger the accessible surface is—i. e., the better the fat is emulsified—the easier it is for enzymes to hydrolyze it (see p. 270). Due to the special properties of milk, milk fats already reach the gastrointestinal tract in emulsified form. Digestion of them therefore already starts in the oral cavity and stomach, where lipases in the saliva and gastric juice are available. Lipids that are less accessible—e.g., from roast pork—are emulsified in the small intestine by bile salts and bile phospholipids. Only then are they capable of being attacked by pancreatic lipase [4] (see p. 270). 

Mun, S., Decker, E.A., McClements, D.J. (2007). Influence of emulsifier type on in vitro digestibility of lipid droplets by pancreatic lipase. Food Research International, 40, 770-781. 

In another set of studies, it has been reported that the in vitro digestibility of lipid droplets by pancreatic lipase is significantly affected by emulsifier type (Mun et al, 2006, 2007 Park et al., 2007). Intuitively, one might expect that a thick dense layer of strongly bound protein-polysaccharide complex at the oil-water interface would reduce considerably the in vivo accessibility of lipases, and hence would reduce the rate of human metabolism of fats. Establishment of the validity of this hypothesis must still await consolidation of a substantial body of detailed results from independent systematic studies on a broad range of mixed biopolymer systems. 

These agents are administered to aid in the digestion of food. The primary digestant preparations contain pancreatic enzymes or bile salts. Pancreatic enzymes such as amylase, trypsin, and lipase are responsible for digestion of carbohydrates, proteins, and lipids, respectively. These enzymes are normally synthesized in the pancreas and secreted into the duodenum via the pancreatic duct. Bile salts are synthesized in the liver, stored in the gallbladder, and released into the duodenum via the common bile duct. Bile salts serve to emulsify lipids in the intestinal tract and are important in lipid digestion and absorption. 

Enzymes are named for what they do. For example, the enzyme given off by the stomach, which splits proteins as part of the digestion process, is called gastric proteinase. The gastric part of the name refers to the enzyme s origin in the stomach. Proteinase denotes that it splits up protein molecules. The common name for this enzyme is pepsin. Similarly, the enzyme produced by the pancreas that breaks down fats (lipids) is called pancreatic lipase. Its common name is... 

It is dear that the interconnection between the activities of the different lipolytic enzymes, where the first enzyme modifies the physicochemical state of the lipid substrate in such a way that it becomes available to another enzyme, is not only of prime importance for lipid digestion, but also results in a broad synergism between gastric lipase, colipase, pancreatic lipase, phospholipase As. calcium, caiboxylester Lipase, bite salts, and substrate interraecK tes [55,62-64]. 

M. UndsttOm, B. Stentby, and B. BotgstrtJrn. Conceited notion of human carboxyl ester lipase and pancreatic lipase during lipid digestion In vitro Impair-... 

Triglycerides are hydrolyzable into their component fatty adds and glycerol. They are espedally susceptible to alkaline hydrolysis. If KOH or NaOH is used, the process is saponification and the products, sodium and potassium salts of fatty adds, are called soaps. In the human organism, triglycerides are hydrolyzed by various esterases called lipases. These enzymes are quite spedfic, and they do not necessarily remove all three fatty add molecules from a triglyceride molecule. Thus, pancreatic lipase, the main lipid digestive enzyme of the small intestine, catalyzes the removal of fatty acids from positions 1 and 3 only. 

To restore nutrient digestion in exocrine pancreatic insufficiency, sufficient enzymatic activity must be administered into the duodenal lumen simultaneously with meal substrates. Intraluminal lipid digestion in postprandial chyme requires lipase activity of at least 40-60 IU/mL throughout the digestive period, which translates into 25,000 to 40,000 IU intraduodenal lipase for digestion of a regular meal. Because plain enzyme preparations undergo rapid lipase inactivation due to acid and proteolytic destruction, it is necessary to administer up to 10-fold more lipase orally to achieve these quantities within the duodenum. 

Drouault, S., Juste, C., Marteau, P., Renault, R, and Corthier, G. (2002), Oral treatment with Lactococcus lactis expressing Staphylococcus hyicus lipase enhances lipid digestion in pigs with induced pancreatic insufficiency, Appl. Environ. Microbiol, 68,3166-3168. 

Q9 Lipid in the diet is present mostly in the form of triglycerides, which are digested by pancreatic lipase to yield fatty acids and monoglycerides bile salts are also required for digestion and absorption of the dietary lipids. Bile salts interact with the fatty acids and monoglycerides in the gut lumen to form micelles, which can be absorbed by the epithelial cells. In the epithelial cell the triglyceride is resynthesized to form droplets, or chylomicrons, which enter the lacteals and are carried by the lymphatic system into the general circulation. 

Bile is produced by hepatocytes from several essential components, including water, bile acids, cholesterol, phospholipids and bilirubin. Most of these substances are absorbed in the distal ileum and delivered to the hepatocyte via the portal vein. The liver excretes approximately 500-600 mL of bile each day, most of which is stored in the gallbladder. Bile acids have an important function in emulsifying lipids in the digestive tract, which improves digestion by pancreatic lipases. 

Pancreatic lipase, with the aid of colipase, digests the triacylglycerols to 2-monoacylglycerols and free fatty acids, which are packaged into micelles. The micelles, which are tiny microdroplets emulsified by bile salts, also contain other dietary lipids such as cholesterol and the fat-soluble vitamins. 

A. Pancreatic lipase catalyzes the breakdown of dietary triacylglycerols into free fatty acids and 2-monoacylglycerols, an essential step in the digestion of dietary lipids. Since prostaglandins are produced from linoleate, an essential fatty add, a deficiency of pancreatic lipase would eventually cause a prostaglandin defidency. 

Bile salts Cholesterol derivatives with detergent-like properties used to solubilize cholesterol, assist in intestinal absorption of fat-soluble vitamins, and emulsify dietary lipids passing through the intestine to enable fat digestion and absorption by exposing fats to pancreatic lipases. 

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