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Cellulose occurs naturally in some foods and is an additive in manufactured foods, contributing an indigestible component used for texture and bulk, potentially aiding in defecation. [ 71 ] Building material: Hydroxyl bonding of cellulose in water produces a sprayable, moldable material as an alternative to the use of plastics and resins.
Ribbon representation of the Streptomyces lividans β-1,4-endoglucanase catalytic domain - an example from the family 12 glycoside hydrolases [1]. Cellulase (EC 3.2.1.4; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides:
Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. Humans and many animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals, such as termites can digest cellulose, because bacteria possessing the enzyme are present in their gut. Cellulose is insoluble in water.
In fact, cellulose has the important function of giving plant cells the rigidity they need to maintain their shape, so varying amounts of it are found naturally in all plants and plant-based foods.
A monogastric digestive system works as soon as the food enters the mouth. Saliva moistens the food and begins the digestive process. (Note that horses have no (or negligible amounts of) amylase in their saliva). After being swallowed, the food passes from the esophagus into the stomach, where stomach acid and enzymes help to
Humans lack the cellulases to digest the carbohydrate cellulose which is a beta-linked glucose polymer. Some of the preceding endogenous enzymes have pharmaceutical counterparts ( pancreatic enzymes ) that are administered to people with exocrine pancreatic insufficiency .
Human food can be classified in various ways, either by related content or by how it is processed. [8] The number and composition of food groups can vary. Most systems include four basic groups that describe their origin and relative nutritional function: Vegetables and Fruit, Cereals and Bread, Dairy, and Meat. [ 9 ]
Xyloglucan binds to the surface of cellulose microfibrils and may link them together. It is the substrate of xyloglucan endotransglycosylase, which cuts and ligates xyloglucans, as a means of integrating new xyloglucans into the cell wall.