Carbohydrates C483 Spring 2013. 1. Examine the Fischer projection below. How is this carbohydrate...
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Transcript of Carbohydrates C483 Spring 2013. 1. Examine the Fischer projection below. How is this carbohydrate...
Carbohydrates
C483 Spring 2013
1. Examine the Fischer projection below. How is this carbohydrate classified?
A) L enantiomer; aldopentose. B) L enantiomer; ketopentose. C) D enantiomer; aldohexose. D) D enantiomer; ketopentose.
2. Which is the proper Haworth projection of β-D-galactopyranose?
3. Which statement is not true about this structure?A. It is a ketoseB. It is a beta anomer.C. It is a furanose.D. It is a pentose.
4. What is the name of the disaccharide shown below that is formed by joining two monomers of D-glucose? A) β-D-glucopyranosyl-(1→4)-β-D-glucopyranose. B) α-D-glucopyranosyl-(1→4)-α-D-glucopyranose. C) β-D-glucofuranosyl-(1→4)-β-D-glucofuranose. D) α-D-glucopyranosyl-(1→3)-β-D-glucopyranose.
Objectives
• Recognize particular carbohydrate structures• Know general structural elements of cyclic
monosaccharides and disaccharides, and their implications for structure/function
• Predict the products of condensation reactions and hydrolysis
Straight-chain Monosaccarides• Aldose/ketose terminology• Triose, tetrose, pentose, hexose• Recognize isomerization (TPI—see page 173)– Should I know the mechanism?
Stereochemistry
• D/L designation• Fisher Projections
Aldose Tree
Ketose Tree
Structures to Know
• D-glucose• D-glyceraldehyde• D-Ribose• D-Galactose• D-fructose• dihydroxyacetone
Cyclic Monosaccharides
• Pyranose• Haworth
Projection• Anomeric carbon• Alpha and beta
anomers
Cyclic Monosaccharides
• Furanose• Just focus on
what is commonly observed– Pyranoses:
glucose, galactose
– Furanoses: ribose, fructose
X
Conformations
• Haworth and chair (no envelopes, etc)
Mutarotase
• Reaction of cyclic carbohydrates which equilibrates anomers
Section 8.4 Sugar Phosphates
Structure of Disaccharides
• Condensation of Monosacharides– Loss of anomeric hydroxyl group and proton of
nucleophilic alcohol– Glycosidic Bond
Structure of Disaccharides
• Nomenclature of linkage– Find the acetal!
• Reducing sugar– Find the hemiacetal!
• “Lactose”– Reducing sugar– Nonreducing sugar– Linkage (number and
stereochemistry)
Polysaccharides
Starch and Glycogen
Cellulose
• Watch structure carefully!
Answers
1. B2. I
3. D4. A