Structure and stereochem of sugars

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  1. Define epimer:
    Epimers: Isomers that differ only in configuaration of a single carbon.
  2. Details about cyclic isoforms of monosaccharides:
    • All monosaccharides with >5 carbons are cyclic in aqueous solution.
    • Carbonyl carbon forms hemiacetal/hemiketal with internal hydroxyl group (intramolecular reaction between aldehyde/ketone and alchohol).
  3. Mutarotation of Glucose: how it comes to be and what results.
    • D-glucose forms an intramolecular hemiacetal between hydroxyl at C-5 and aldehyde at C-1.
    • Results in 2 cyclic anomers (special case of epimers): alpha/beta-D-glucopyranose.
  4. Define pyranose:
    • A 6-membered ring.
    • Aldohexoses form 6-membered rings.
  5. Define funranose:
    • A 5-member ring.
    • Ketohexoses and aldopentoses form 5-member rings.
  6. What are derivatives of monosaccharides?
    • It is when hydroxyl groups of monosaccharides are replaced with other groups such as amino groups.
    • It can happen when oxidation of C1 carbonyl group occurs --> aldonic acid.
    • It can happen when oxidation of carbon farthest from carbonyl group , C6, occurs --> uronic acid.
  7. Define glycosidic bond:
    What can this bond do?
    • Glycosidic bond: Anomeric carbon of one sugar reacts with hydroxyl group of another sugar.
    • The glycosidic bonding converts hemiacetal/hemiketal into acetal/ketal and produces H2O.
    • The process of glycosidic bonding is slow, these bonds don't break easily.
  8. Define Anomer:
    • Anomers: differ only in the configuration of the hemiacetal or hemiaketal carbon.
    • Anomers are found on the reducing end of cyclic glucose, anomeric carbon.
  9. Define disaccharides:
    Monosaccharides joined by O-glucosidic bonds by process of condensation, H2O is a product in creating disccharaides.
  10. What are biologically important disaccharides?
    • Disaccharides that are non-reducing.
    • Bond is formed between two anomeric carbons. Double-headed arrow connects anomeric carbons. (beta2 <-> 1alpha).
Card Set:
Structure and stereochem of sugars
2014-03-09 20:57:47
Chapter MCDB

Chapter 7, MCDB
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