Carbohydrate chemistry ppt Lecture3 BIOCHEMISTRY

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Glycosaminoglycans or mucopolysaccharides

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  • Chondroitin-4-sulfate (Greek: chondros, cartilage), amajor component of cartilage and other connective tissue, has N-acetyl-D-galactosamine-4-sulfate residues in place ofhyaluronate’sN-acetyl-D-glucosamine residues.
  • Chondroitin-4-sulfate (Greek: chondros, cartilage), amajor component of cartilage and other connective tissue, has N-acetyl-D-galactosamine-4-sulfate residues in place ofhyaluronate’sN-acetyl-D-glucosamine residues.
  • Keratan sulfate (Greek: keras, horn; not to be confusedwith the protein keratin) consists mainly of alternating(1 S4)-linked D-galactose and N-acetyl-D-glucosamine-6-sulfate residues (and hence lacks uronic acid residues). It isa component of cartilage, bone, cornea, as well as hair,nails, and horn. Keratan sulfate is the most heterogeneousof the major GAGs in that its sulfate content isvariable and it contains small amounts of fucose, mannose,N-acetylglucosamine, and sialic acid.5. Heparin is a variably sulfated GAG that consists
  • Keratan sulfate (Greek: keras, horn; not to be confusedwith the protein keratin) consists mainly of alternating(1 S4)-linked D-galactose and N-acetyl-D-glucosamine-6-sulfate residues (and hence lacks uronic acid residues). It isa component of cartilage, bone, cornea, as well as hair,nails, and horn. Keratan sulfate is the most heterogeneousof the major GAGs in that its sulfate content isvariable and it contains small amounts of fucose, mannose,N-acetylglucosamine, and sialic acid.5. Heparin is a variably sulfated GAG that consists
  • Heparin is a variably sulfated GAG that consists predominantlyof alternating (1 S 4)-linked residues of Liduronate-2-sulfate and N-sulfo-D-glucosamine-6-sulfate.It has an average of 2.5 sulfate residues per disaccharideunit, which makes it the most negatively charged polyelectrolytein mammalian tissues (Fig. 11-23). Heparin, in contrastto the above GAGs, is not a constituent of connectivetissue, but occurs almost exclusively in the intracellulargranules of the mast cells that line arterial walls, especiallyin the liver, lungs, and skin. It inhibits the clotting of blood,and its release, through injury, is thought to prevent runawayclot formation (Section 35-1Ea). Heparin is thereforein wide clinical use to inhibit blood clotting, for example, in
  • Heparin is a variably sulfated GAG that consists predominantlyof alternating (1 S 4)-linked residues of Liduronate-2-sulfate and N-sulfo-D-glucosamine-6-sulfate.It has an average of 2.5 sulfate residues per disaccharideunit, which makes it the most negatively charged polyelectrolytein mammalian tissues (Fig. 11-23). Heparin, in contrastto the above GAGs, is not a constituent of connectivetissue, but occurs almost exclusively in the intracellulargranules of the mast cells that line arterial walls, especiallyin the liver, lungs, and skin. It inhibits the clotting of blood,and its release, through injury, is thought to prevent runawayclot formation (Section 35-1Ea). Heparin is thereforein wide clinical use to inhibit blood clotting, for example, in
  • Carbohydrate chemistry ppt Lecture3 BIOCHEMISTRY

    1. 1. Carbohydrate chemistry III GLYCOSAMINO GLYCANS Dr. Vijay Marakala, MD. Assistant professor BIOCHEMISTRY SIMS & RC
    2. 2. POLYSACCHARIDES • These are formed by the condensation of n molecules of monosaccharides with the removal of n-1 molecules of water. Since condensation involves the carbonyl groups of the sugars, leaving only one free carbonyl group at the end of a big molecule, polysaccharides are non-reducing. • They are of 2 types: 1. Homopolysaccharides (e.g. Starch, Glycogen, cellulose). 2. Heteropolysaccharides (e.g. glycosaminoglycans, glycoproteins)
    3. 3. Glycosaminoglycans or Mucopolysaccharides
    4. 4. GAGs Structure of GAGs Occurrence of GAGs Functions of GAGs Types of GAGs
    5. 5. Structure of GAGs • A GAG is an unbranched polysaccharide, made up of repeating disaccharides. • One component is always an aminosugar • Other component is uronic acid(except keratan sulfate) • All the GAGs contain sulfate group(except hyaluronic acid) • Thus GAGs are a polymer of [uronic acid- amino sugar]n
    6. 6. Occurrence of GAGs • Proteoglycans are found in the: a) Synovial fluid of joints b) Vitreous humour of the eye c) Arterial wall d) Bones e) Cartilage
    7. 7. Functions of GAGs • Major components of the extracellular matrix • Producing a gel like matrix which functions as a cushion against mechanical shocks. • They lubricate joints • They also give resilience (elasticity) to cartilage
    8. 8. Types of GAGs Hyaluronic acid Condroitin sulfate Keratan sulfate Dermatin sulfate Heparin Heparin sulfate
    9. 9. Hyaluronic acid • N-acetyl glucosamine-Glucuronic acid Disaccharide unit • Synovial fluid, vitreous humour Location • Serve as lubricant and shock absorber Function
    10. 10. Condroitin sulfate • N-acetyl galactosamine-Glucuronic acid Disaccharide unit • At sites of calcification in bone and cartilage Location • Provide an endoskeletal structure Function
    11. 11. Keratane sulfate • N-acetyl glucosamine-Galactose Disaccharide unit • Cornea, loose connective tissue, cartilage Location • Transparency of cornea Function
    12. 12. Heparin • Glucosamine-Glucuronic acid Disaccharide unit • Intracellular component of mast cell Location • Serves as an anticoagulant Function
    13. 13. Glycoproteins •Protein component is predominant •<4% carbohydrate Proteoglycans •Carbohydrate is major component •>4% carbohydrate
    14. 14. • Define carbohydrates. Classify them and give two examples for each class/subclass. Write a note on biological importance of carbohydrates.(10) • Glycosaminoglycans/Mucopolysaccharides.(5) • Polysaccharides.(5) • Isomerism and stereoisomerism.(5) • Biological importance of carbohydrates.(5) • Mutarotation.(3) • Starch and glycogen.(3) • Write composition of following, indicating their linkages.(3) • (a) SUCROSE (b) MALTOSE (c) LACTOSE. IMORTANT QUESTIONS

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