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Digestive Enzymes

Posted by on Saturday, April 9, 2011, 4:23
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Digestive enzymes are enzymes in the alimentary tract with a purpose of breaking down components of food so that they can be taken up by the organism. Digestive enzymes include pancreatic enzymes, plant-derived enzymes, and fungal-derived enzymes. Different enzymes with different functions. In humans, digestion begins in the mouth where food is chewed with the teeth. The process stimulates exocrine glands in the mouth to release digestive enzymes such as salivary amylase, which aid in the breakdown of food, particularly carbohydrates.

Digestive Enzymes
Digestive Enzymes

What’re enzymes?

Enzymes are protein molecules t produced within an organism that are used a catalysts for biochemical reactions. In other words, enzymes act as catalysts for organic biochemical reactions speeding the rate at which a biochemical reaction proceeds but not altering the direction or nature of the reaction. Enzymes are biological catalysts. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it otherwise would. Enzymes can accelerate, often by several orders of magnitude, reactions that under the mild conditions of cellular concentrations, temperature, pH, and pressure would proceed imperceptibly (or not at all) in the absence of the enzyme. In enzymes, as with other proteins, function is determined by structure. An enzyme can be a monomeric protein made up of about hundred amino acids or more, or an oligomeric protein consisting of several monomers, different or identical, that act together as a unit.

Enzymes act on substrates to yield products, they facilitate chemical reactions but are not changed by the reaction. Enzymes are necessary within biological cells because most chemical reactions required by the cell would occur too slowly to sustain life. Enzymes can increase reaction rate by favoring or enabling a different reaction pathway with a lower activation energy, making it easier for the reaction to occur. The overall rate of enzyme mediated reactions depends on many factors. Enzymes are essential to living organisms, and a malfunction of even a single enzyme out of approximately 2,000 types present in our bodies can lead to severe or lethal illness. Enzymes are generally named by adding the ending “-ase” to the name of the substance on which the enzyme acts (for example, protease is an enzyme that acts on proteins).

Digestion and digestive system
Digestion is the process by which organisms break down sludge, creating as by-products methane gas, carbon dioxide, solid organic material and water. Digestion involves physically breaking down the food by chewing and churning in the stomach. Food is also chemically broken down by digestive juices that are produced in the stomach and other parts of the digestive tract. Starts in the mouth, continues in the stomach and small intestine, and is completed in the large intestine. Digestive systems are the organs in the body that break down and absorb food. Organs that make up the digestive system are the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus. Organs that help with digestion but are not part of the digestive tract are the tongue, glands in the mouth that make saliva, pancreas, liver, and gallbladder. The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste. In the stomach, food is churned and thoroughly mixed with acid and other digestive enzymes with digestive fluid to further decompose it chemically. As the acidic level changes in the stomach and later parts of the digestive tract, more enzymes are activated or deactivated to extract and process various nutrients. After being processed in the stomach, food is passed to the small intestine through the pyloric sphincter where it is further mixed with secretions such as bile, which helps aid in fat digestion, and the enzymes maltase, lactase and sucrase, to process sugars.

Functions of digestive enzymes
Digestive enzymes are complex proteins involved in digestion that stimulate chemical changes in other substances. Digestive enzymes help break down these complex sugars into simple sugars that are more easily digestible. Nutrition in animals relies on digestive enzymes such
as salivary amylase, trypsin and chymotrypsin. Their primary role is for the digestion of food and making nutrients available to all of the body processes which need them. The main sites of action are the oral cavity, the stomach, the duodenum and the jejunum. They are secreted by different glands: the salivary glands, the glands in the stomach, the pancreas, and the glands in the small intestines.

In the oral cavity, salivary glands secrete pytalin. It is a type of α-amylase, which digests starch into small segments of multiple sugars and into individual soluble sugars. Secreted by small and large salivary glands. The enzymes that get secreted in the stomach are called gastric enzymes. Pepsin is the main gastric enzyme. As it breaks proteins into smaller peptide fragments, it is a peptidase. Gelatinase, degrades type I and type V gelatin and type IV and V collagen, which are proteoglycans in meat. Gastric amylase degrades starch, but is of minor significance. Gastric lipase is a tributyrase by its biochemical activity, as it acts almost exclusively on tributyrin, a butter fat.

The pancreas is the main digestive gland in our body. It secretes many enzymes. Trypsin, is a peptidase, like pepsin in the stomach. Chymotrypsin, also a peptidase. Carboxypolypeptidase, splits peptide fragments into individual amino acids. It is a protease. Several elastases that degrade the protein elastin and some other proteins. Several nucleases that degrade nucleic acids. Pancreatic amylase that, besides starch and glycogen, degrades also most other hydrocarbons, but not cellulose. Disaccharides and trisaccharides form. Four types of enzymes degrade disaccharides into monosaccharides. Sucrase breaks down sucrose intp glucose and fructose. Maltase breaks down maltose into glucose. Isomaltase breaks down maltose and isomaltose. Lactase breaks down lactose into glucose and galactose. Intestinal lipase breaks down fatty acids.

Major supplemental digestive enzymes
Amylase - Amylase is an enzyme that changes complex sugars (starches) into simple sugars during digestion. Amylase hydrolyzes starch,
glycogen, and dextrin to form in all three instances glucose, maltose, and the limit-dextrins. Amylase is secreted by the salivary glands and the pancreas that helps in the digestion of carbohydrates.

Bromelain - Bromelain is an enzyme found in pineapples that breaks down other proteins, such as collagen and muscle fiber. Bromelain is a mixture of sulfur-containing protein-digesting enzymes, called proteolytic enzymes or proteases. Bromelain is mainly comprised of cysteine proteases, with smaller amounts of acid phosphatase, peroxidase, amylase and cellulase.

Cellulase - Cellulases are a group of enzymes catalyzing an enzymatic reaction system in which cellulose is decomposed into glucose, cellobiose or cellooligosaccharides. Cellulase is an enzyme complex which breaks down cellulose to beta-glucose. Cellulases are key industrial enzymes used to breakdown biomass to fermentable sugars.

Lactase - Lactase (or beta-galactosidase) is the enzyme involved in the hydrolysis of lactose to galactose and glucose. Lactose is a disaccharide consisting of two subunits, a galactose and a glucose linked together. Lactose is an abundant disaccharide which is present in milk and in certain dairy products such as yogurt and whey.

Lipase - Lipase is an enzyme secreted by the pancreas into the small intestines. Lipase is an enzyme necessary for the absorption and digestion of nutrients in the intestines. Lipase catalyzes the breakdown of triglycerides into fatty acids. As with amylase, lipase appears in the blood following damage to the pancreatic acinar cells.

Pancreatin - Pancreatin is the mixture of enzymes obtained by extraction of the pancreas and consisting essentially of lipases, amylase and proteases. Pancreatin hydrolyses fats, changes protein into proteoses and derived substances and converts starches into dextrins and sugars. Pancreatin is a digestant that is used in the treatment of pancreatic insufficiency as pancreatic enzyme replacement.

Papain - Papain is in the dried latex obtained from the papaya fruit (Carica papaya L). Papain hydrolyzes proteins to form oligopeptides and amino acids. Papain has milk-clotting (rennet) and protein digesting properties. Papain has the ability to digest dead tissue without affecting the surrounding live tissue.

Pepsin - Pepsin is a digestive enzyme found in gastric juice that catalyzes the breakdown of protein to peptides. Pepsin is one of three principal protein-degrading, or proteolytic, enzymes in the digestive system. Pepsin degrades food proteins in the stomach. Pepsin acts as a potent proteolytic enzyme cleaving proteins into peptides in the gastric lumen at a low pH.

Chymotrypsin - Chymotrypsin is a pancreatic digestive enzyme that catalyzes the hydrolysis of certain proteins in the small intestine into polypeptides and amino acids. Chymotrypsin hydrolyzes the peptide bond of amino acids with large hydrophobic side chains, such as phenylalanine, tryptophan, and tyrosine.

Trypsin - Trypsin is a proteolytic enzyme that hydrolyzes peptide bonds on the carboxyl side of the amino acids arginine and lysine. Trypsin catalyzes the cleavage and activation of additional trypsinogen and other pancreatic proenzymes important to protein digestion.

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