Polysaccharides Lecture Notes PDF

Polysaccharides Dr. Uzma Nasib YOU STUDY TO PREPARE FOR THE DAY WHEN YOU ARE THE ONLY THING …. BETWEEN A PATIENT AND A GRAVE Mark Reid  Learning Objectives By the end of the lecture students will be able to know about: Polysaccharide Its types Uses Fun...

Polysaccharides Dr. Uzma Nasib YOU STUDY TO PREPARE FOR THE DAY WHEN YOU ARE THE ONLY THING …. BETWEEN A PATIENT AND A GRAVE Mark Reid  Learning Objectives By the end of the lecture students will be able to know about: Polysaccharide Its types Uses Function  Today’s Patients Skeletal Deformities, enlarged head, lips, cheeks, tongue, and nose, vocal cords, resulting in a deep voice. (mental retardation ) Polysaccharides non-sugars, insoluble, high molecular weight Functions: 1. food and energy 2. structural materials 6  Starch Is a polymer of -glucose Stored as starch grains in: Chloroplasts Storage organs Seeds 15 Convenient storage materials because they:- are easily hydrolysed to sugars amyla malta STAR se MALTO se GLUCO CH SE SE hydrolysis 17  Pure starch is a white, tasteless and odorless powder Insoluble in cold water or alcohol. It consists of two types of molecules: The linear and helical amylose The branched amylopectin. Amylose, linear chain connected by α(1→4) glycosidic bonds Amylose Fragment  Types of amylases: 2 broad classes of amylases exist as: – α-amylase is present in saliva and pancreatic juice – β-amylase is present in sprouted grains and malts. Both of them hydrolyse only α- glycosidic linkage mylopectin, branched chain. ontain both (α1→4) and (α1→6 ) linkages. CH2 OH CH2 OH H O H H O H H ( OH H amylopectin O H OH H H OH O H OH O (-1,6 link) CH2 OH CH2 OH CH2 CH2 OH H O H H O H H O H H O H ( OHH H H H O H OH H OH H OH H O O O O) H OH H OH H OH H OH  AMYLOSE AMYLOPECTIN Straight chain (non- Branched chains branching) α-1 – 4 linkage α -1 – 4 & 1 – 6 linkage. 13 – 20% 80 – 85% 250 – 300 glucose 24 – 30 glucose residue residue Water soluble Water insoluble (when absorb water  swell) Iodine  blue color Iodine  violet color  Glycogen D-Glucoses linked by α-1,4 & α-1,6 glycosidic bonds Branching after 8-10 residues Inulin (Fructosan) Storage polysaccharide  polymer of D-fructose, -(1,2) linked fructofuranoses -Linear ,no branching -Lower molecular weight than starch -Colors yellow with iodine -Hydrolysis yields fructose -Sources include onions, garlic, dandelions and Jerusalem artichokes (roots of sunflower tree). Jerusalem artichoke 28  The functions of dietary fiber The water holding capacity is very high, so they ↑ bulk of stools & facilitate the passage through the colon which help prevent constipation and incidence of colon cancer. They bind with the blood cholesterol and reduce its absorption from the intestinal tract Too much fiber increases abdominal fullness. Homopolysaccharide Storage Polysaccharide Structure Polysaccharide Starch Cellulose Glycogen Chitin  Heteropolysaccharides Glycosaminoglycans (Mucopolysaccharides) The Glycosaminoglycans are linear polymers constituted by disaccharides (aminosugar- acidsugar). One of the monosaccharides is always N-acetylglucosamine or N- acetylgalactosamine. The other one is either D-glucuronic or L-iduronic (Iduronic acid epimer Mucopolysaccharidoses (MPS)are a group of metabolic disorders caused by the absence or malfunctioning of lysosomal enzymes needed to break down molecules called glycosaminoglycans.  Mucopolysacchari doses Are genetic disorders of proteoglycan metabolism they are characterized by the excessive accumulation and excretion of glycosaminoglycans Cause: Deficiencies of lysosomal enzyme that are responsible for the degradation of mucopolysaccharides. Hyaluronic Acid  PROTEOGLYCANS Proteoglycans are conjugated proteins. Proteins called“core” proteins are covalently linked to glycosaminoglycans