Carbohydrates

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Carbohydrates
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Definitions
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• Carbohydrates Cn(H2O)n
• Glucose C6H12O6 C6(H2O)6
• polyhydroxyaldehydes
• aldohexose (glucose)
• polyhydroxyketones
• ketohexose (fructose)

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Composition
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• Monosaccharides
• glucose
• galactose
• fructose
• Disaccharides
• maltose
• lactose
• sucrose

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• Polysaccharides
• Plants
• cellulose - structure
• starch - storage
• Animals
• glycogen storage
• glucose energy
• All are polyglucose

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Chirality
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• Optical isomers

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Fischer Projections
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Two chiral carbons on each. Which carbon is
carbon 1? Which carbon is the highest numbered
chiral carbon? Which are D isomers? Which are
L isomers? Which are enantiomers? Which are
diastereomers?
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Physical Properties
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• All simple sugars are water soluble.
• Sugars have high boiling points and are mostly
  solids at room temperature.
• Sugars are sweet-tasting, digestible and
  non-toxic. (Glycols are sweet-tasting and
  poisonous.)
• Enantiomers
• Have similar chemical properties
• Rotate polarized light in different directions.
• Chirality causes reaction specificity.

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Hayworth Formulas
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• Pyranose ring (aldohexoses)
• Furanose ring
• (ketohexoses)

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Ring formation
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Hemiacetal formation -OH groups pointing
left in Fischer projection will point up in the
Hayworth formula.
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Anomers
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ß-D-glucose
a-D-glucose
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• Ordinarily, crystalline glucose is entirely in
  a-form.
• Once dissolved in water, equilibrium is
  established between the open chain and two
  anomeric form of the glucose.

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Anomers of Fructose
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Reactions of Sugars
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• Rings that form as hemiacetals act as reducing
  agents and are called "reducing sugars." The
  rings that are hemiacetals are called "unlocked
  rings."
• Sugars that form acetals are not reducing agents
  and are called "locked rings." (Sucrose is a
  non-reducing sugar)

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Phosphate Esters
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glucose-6-phosphate
glucose-1-phosphate
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Amino Sugars (ABO blood type)
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• Type A a-D-N-acetylgalactosamine

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• Type B a-D-galactosamine

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• Type O L-fucose (a deoxy sugar)

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• antigen antibody
• Type A (40) A B
• Type B (15) B A
• Type AB (5) A and B none
• Type O (40) none A and B
• Universal donor O Universal receiver AB
• Rh is another factor that is commonly recorded.
  85 of the population is Rh positive.

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Disaccharides
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• 1. Maltose
• a. 2 glucose units in an a(1,4) linkage
• b. Reducing sugar
• 2. Lactose
• a. Glucose galactose in a ß(1,4) linkage
• b. Reducing sugar

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• 3. Sucrose
• a. Glucose fructose in an a(1,2) linkage
• b. Non-reducing sugar

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Polysaccharides
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• Plants
• a. amylose
• a(1,4) glucose chain

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• b. amylopectin
• a(1,4) glucose chain with a(1,6) glucose branches
  every 20 25 units

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• c. cellulose
• ß(1,4) glucose chain
• Insoluble in water because of hydrogen bonding
  between chains

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• 2. Animal glycogen
• a(1,4) glucose chain with a(1,6)
• glucose branches every 10 12 units