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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:
Starches are insoluble in water. They can be digested by breaking the alpha-linkages (glycosidic bonds). Both humans and other animals have amylases so that they can digest starches. Potato, rice, wheat, and maize are major sources of starch in the human diet. The formations of starches are the ways that plants store glucose. [14]
Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts, such as Trichonympha. In human nutrition, cellulose is a non-digestible constituent of insoluble dietary fiber, acting as a hydrophilic bulking agent for feces and potentially aiding in defecation.
l-Glucose does not occur naturally in living organisms, but can be synthesized in the laboratory. l -Glucose is indistinguishable in taste from d -glucose, [ 1 ] but cannot be used by living organisms as a source of energy because it cannot be phosphorylated by hexokinase , the first enzyme in the glycolysis pathway.
Dietary fiber (fibre in Commonwealth English) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. [1] Dietary fibers are diverse in chemical composition and can be grouped generally by their solubility, viscosity and fermentability which affect how fibers are processed in the body. [2]
Amylose A is a parallel double-helix of linear chains of glucose. Amylose is made up of α(1→4) bound glucose molecules. The carbon atoms on glucose are numbered, starting at the aldehyde (C=O) carbon, so, in amylose, the 1-carbon on one glucose molecule is linked to the 4-carbon on the next glucose molecule (α(1→4) bonds). [3]
Adults didn’t naturally produce the enzyme needed to be able to digest the lactose in milk, but gradually many of us evolved to be able to tolerate it — with milk eventually becoming a staple ...
Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic (about 5.6 ~ 6.9). Some vitamins, such as biotin and vitamin K (K 2 MK7) produced by bacteria in the colon are also absorbed into the blood in the colon. Absorption of water, simple sugar and alcohol also takes place in stomach.