NUTR 4320 Study Guide - Final Guide: Hydrogen Breath Test, Lactose Intolerance, Lactase
24 Dec 2016
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Disaccharidase deficiencies: leads to intolerance to dietary disaccharides lactose, sucrose, maltose. Usually occurs because of a deficiency in one or more mucosal enzymes. Digestive enzymes for cho on gut lumen. Oligomers 5-10 unit mono-saccharides uptake by specific membrane transporters. Transport may occur by facilitated diffusion or active transport. Glut 2, glut 5 - facilitated - small intestine. Glut 6 (sglt1) - na+/glc cotransport small intestine. Secondary active transporter, b/c depends on creation of a sodium gradient. Lactose intolerance an inherited or acquired inability to digest lactose due to deficiency in catalytically active. Lactase enzyme abbr lph (lactose phlorizin hydrolase) lactose lactase-phlorizin hydrolase two activities phlorizin glucose+galactose ( -glycosylceromides) Two subsequent duplications of one ancestral gene duplicate b-gal, activate it, phlorizin hydrolase. Homology with -galactosidases: archae, eubacteria, and fungi (size: 50 kd) earlier form of the enzyme. Small intestinal epithelial cells as a single chain 215 kda, pro-lph precursor mannose-rich n- glycosylated. Two folded subunits form homodimer which leaves the er.
