BCH210H1 Lecture Notes - Lecture 23: Abo Blood Group System, Asymmetric Carbon, Fischer Projection
25 May 2018
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Lecture 23: Carbohydrates
Carbohydrates in Biochemistry
• Bacterial cell walls contain polysaccharides in their peptidoglycan layer
- Antibiotics inhibit synthesis of these structures
• Agarose and agar are polysaccharides used to run DNA gels and for
microbial plates
• Glycosylation (adding sugar chains) of proteins leads to increased
diversity and protein complexity
- Membrane proteins exposing sugar chains
• Lectins are proteins that are able to bind to sugars (recognize)
• Protein glycosylation assists in folding and cellular recognition (eg. ABO blood groups)
ABO Blood Group Antigens
• Conformation of a sugar is vital for its ability to bind to the targets in the body or be recognized by antibodies
• Different sugars = different antigens
Sugar Structures
• Glucose – 6 membered ring
• Fructose – 5 membered ring
• Sucrose (disaccharide) – glucose AND fructose
• Different structures but similarities – lots of hydroxyls (-OH) = lots of
hydrogen bonds = soluble in water
Siplest Moosaccharides C∙H2O
• 3 carbon sugars – (C+H20)n where n is 3 or larger
• Hydroxyl groups AND carbonyl functional groups
• Aldo-3-oses – carbonyl at carbon 1 forming aldehyde (glyceraldehyde)
• Ketone with carbonyl (dihydroxyl acetone)
• Carbonyl gets priority in numbering
• Isomers – hydroxyl on left is L-isomer and hydroxyl on right is D-isomer
• Same molecular formula 3 carbons, 6 hydrogens and 3 oxygens (isomers)
Carbohydrate Configuration
• Fischer projection – flat arrangement
• Carbons increase – triose, tetrose, pentose,
hexose
• Aldehyde is where carbon 1 is located always
• Asymmetric when different groups on carbons
- Hydroxyl on right or left
- Last chiral carbon (asymmetric carbon)
gives D or L designation
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BCH210H1 Full Course Notes
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Document Summary
Carbohydrates in biochemistry: bacterial cell walls contain polysaccharides in their peptidoglycan layer. Antibiotics inhibit synthesis of these structures: agarose and agar are polysaccharides used to run dna gels and for microbial plates, glycosylation (adding sugar chains) of proteins leads to increased diversity and protein complexity. Lectins are proteins that are able to bind to sugars (recognize: protein glycosylation assists in folding and cellular recognition (eg. abo blood groups) Abo blood group antigens: conformation of a sugar is vital for its ability to bind to the targets in the body or be recognized by antibodies, different sugars = different antigens. Sugar structures: glucose 6 membered ring, fructose 5 membered ring, sucrose (disaccharide) glucose and fructose, different structures but similarities lots of hydroxyls (-oh) = lots of hydrogen bonds = soluble in water. Isomers hydroxyl on left is l-isomer and hydroxyl on right is d-isomer.
