BIOS 452 Lecture Notes - Lecture 19: Glycosidic Bond, Lactose Intolerance, Reducing Sugar
Document Summary
Monosaccharides= simple sugar, monomer, abundant in d-glucose dextrose . Oligosaccharides= short chains(<20), mono joined by glycosidic bonds. 2^n stereoisomers(enantiomers) when n= # chiral centers most common simple sugar= d-glucose, d-fructose. Alpha and beta anomers of d-glucose interconvert to make 1/3 alpha and 2/3 beta in equilibrium. Fehling"s reaction= amount of oxidizing agent reduced by the sugar, (diabetes test) Tollen"s test= distinguishes aldehyde and ketone(aldehyde can reduce ag+ to ag0) Anomeric oh replaced by o of oh of another sugar via condensation. Lactose intolerance= no enzyme to hydrolyze b1->4 link. Sucrose= ad glucose+ bd fructose via a1->2b linkage. Both anomeric bonds are used for glycosidic likage, makes sucrose a non reducing sugar. Polymer d-glucose, glycogen is more extensively branched. Cellulose is not digestible because we don"t have b1-4. Glycogen and starch on the other hand are broken down via enzymes in saliva working on a1-4 breaks. Bulky pyranose rinks strain phi-psi angles between a1-4 links.
