User:Benjah-bmm27/degree/3/MCG
Appearance
Carbohydrates, MCG
[edit]Important functions and applications
[edit]- Salicin and its derivative, aspirin: Jmol
- Heparin and related anticoagulants: low molecular weight heparin, fondaparinux, idraparinux
- ABO blood group system
Common sugars
[edit]- Glucose: Jmol models from the crystal structures of both the α and β anomers.
- Galactose
- Mannose
- Fucose — the only sugar that naturally occurs as the L-enantiomer
- Fructose
Carbohydrate structures and conformations
[edit]Hemiacetals and mutarotation
[edit]- Hemiacetal formation
- alcohol + aldehyde → hemiacetal
- acid promotes forward reaction, base promotes reverse
- new chiral centre formed
- In monosaccharides, the new chiral centre is called the anomeric carbon
- Mutarotation of hemiacetals
- α and β anomers of monosaccharides interconvert
- α hemiacetal → aldehyde + alcohol → β hemiacetal
- In solution, glucose is:
- 36 % α-D-glucopyranose
- 63 % β-D-glucopyranose
- 0.003 % open chain aldehyde
- negligible proportions exist as α-D-glucofuranose and β-D-glucofuranose
Ring conformation
[edit]- For glucose, 4C1 conformation preferred to 1C4 as the former has all equatorial groups, latter has all axial