POLYSACCHARIDES 1. Homopolysaccharides D-glucose Amylose Starch D-glucose Glycogen Cellulose Amylose a-(1-4) D-glucose GLUCANS Amylopectin a-(1-4) D-glucose, a-(1-6) D-glucose Glycogen b-(1-4) D-glucose Cellulose

HOMOPOLYSACCHARIDES Branch point

GLYCOGEN Non-reducing Ends Reducing End

Glycogen is built for glucose storage and rapid glucose release….. Highly branched Macromolecular Multi ends Cellulose is built for support. The molecules emphasizes extended chains with close packing b-1-4 linkage Alternate glucose units are flipped

Digestive Enzymes a Starch Amylose Amylases Will not digest Cellulose Break internal a-1-4 bonds a-1-4 glycosidic bond Non Reducing End Will not digest Cellulose a -glucosidase Maltose and maltotriose are the major products Maltase D-glucose units

Debranching Enzyme Limit Dextrin amylases Amylopectin or Glycogen -1-4, -1-6 glucosidase or Debranching enzyme Glycogen Phosphorylase: Inserts the elements of phosphate across the glycosidic bond-NOT Digestive

HETEROPOLYSACCHARIDES Salivary Secretions Nature’s Lubricants Vitreous Humor Slimy, mucous, substances Joints Synovial fluid GLYCOSAMINOGLYCANS (GAGS) Chondroitin Sulfate Hyaluronic Acid Keratan Sulfate Dermatin Sulfate Heparin Repeating unit is a Negatively charged disaccharide

Heteropolysaccharides Amino Sugars O CH2OH NH C=O CH3 Amine group on carbon 2 Acetyl group on amine Amino sugars are always acetylated

HETEROPOLYSACCHARIDES Sulfate Sugars Uronic Acids O CH2OSO3 NH C=O CH3 = O COO Negative Charge D-glucuronic acid (GlcUA) N-acetylgalactosamine- 6-sulfate (GalNac-6s)

Repeating unit of CHONDROITIN 6 SULFATE b 1-3 b 1-4 = = O O O CH2OSO3 NH C=O CH3 = O COO O CH2OSO3 NH C=O CH3 = COO O O Repeating disaccharide Repeating unit of CHONDROITIN 6 SULFATE

Proteoglycans proteins with one or more covalently linked GAG chains Link Protein Core protein GAG Hyaluronate

Protein is the Major component GLYCOPROTEINS C=O CH2 N C O Protein is the Major component Asparagine linkage

Bi-Antennary Typical Oligosaccharide Chain in a Glycoprotein Sia Sia Gal Gal GlcNAc GlcNAc Man Man Man Bi-Antennary Typical Oligosaccharide Chain in a Glycoprotein GlcNAc GlcNAc Asn

Carbohydrates in Proteins are Information Molecules Diversity allows recognition patterns to vary:  or  configuration on C-1 Linking -OH groups on different positions Types of sugars and presence or absence of branching Presence or absence of sialic acid Patterns guide biological processes Carbohydrate-binding proteins (lectins) recognize specific patterns or features and interact with specific sites on oligosaccharide chains

Carbohydrate-binding Proteins (lectins) Recognize oligosaccharide chains on cell membranes Examples: Plant lectins: concanavalin A (-mannose residues) wheat germ agglutinin (GlcNAc-GlcNAc-GlcNac) peanut lectin (Gal (1-3)-GalNac) [Physiological role uncertain; binding of rhizobium bacteria to root hairs for nitrogen fixation is one function].

Asialoglycoprotein Receptor on surface of liver cells: Allows liver to remove old proteins that have lost their sialic acid from the circulation Exposed galactose residue is the signal for removal Mannose-6-Phosphate Receptor: Targets proteins for destruction in the lysosomes ZP3 Receptor on surface of sperm: ZP3 glycoprotein in extracellular coat of ovulated eggs -linked galactose at the non-reducing end Binding triggers release of sperm enzymes, dissolves zona pellucida to allow sperm to enter

Selectins: (Carbohydrate-binding adhesive proteins) Surface of neutrophils, lymphocytes, leukocytes Interacts with carbohydrates on endothelial cells, lymph-node vessels and platelets E-selectins recognize injured endothelial cells Binds lymphocytes to endothelial cells in order to penetrate into underlying cell layer Creates and perpetuates an inflammatory condition L-selectins allow circulating lymphocytes to return to sites in lymph nodes from which they were derived… return is called homing Binding mediated by Ca2+ Prevented by removal of sialic acid