1. Lecture IX Polysaccharides I
Structural Determination
Lecture #9 - Polysaccharides I - Determination of structure
Will cover
Structural Determination of PSs (general principles only)

2. CHO Classification I
Monosaccharides
Oligosaccharides
Polysaccharides

3. CHO Classification V Polysaccharides > 20 monosaccharide units
Homo- and heteroglycans
Linear
Branched
Note: DP = Degree of Polymerization

4. Carbohydrate Structure I
Monosaccharides
Glycosides
Oligosaccharides
Polysaccharides
Generalizations I

5. Carbohydrate Structure I
Monosaccharides
Glycosides
Oligosaccharides
Polysaccharides
Generalizations II
polydisperse = range of MW
polymolecular=linkages vary….
A polydisperse collection

6. Polysaccharide Structure
Preparation/Purification
Remove foreign material
Extraction/Isolation
Filtration, dialysis, etc.
Precipitation

7. Lignin Wood = cellulose + lignin(20-30%)
Lignin = non-CHO polymer, contain-ing aromatic rings bearing -OCH3 (methoxyl) groups. Methanol derived from wood comes from the lignin component (hence, MeOH = “wood alcohol”)

8. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Ring size(s)
Anomeric configurations
Linkage types
Sequence of sugar residues
Substituent groups
DP/MW/Higher Orders of Structure

9. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Hydrolysis
HPLC and/or GLC
Structure of Heparin

10. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues HPLC (
Separation of sugar anomers

11. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Linkage types/ring sizes
Methylation analysis

12. Reactions of Carbohydrates III Hydroxyl Groups- Ether Formation
Methylation analysis
Methylate polysaccharide
Hydrolyze (acid)
Analyze hydrolizate
Deduce where PS linkages were

13. Methylation Analysis I
CH2OH OH HO A
CH2 B C
ROH RO-
30% NaOH
For example ……..
1. Strong base in DMSO
2. Methyl Iodide (Me I) O
CH2OMe
OMe
MeO A
CH2 B C
90% formic acid
100o, 1 hr
Note, “Me” = CH3-

14. Methylation Analysis II
MeO O
CH2OMe
OMe A OH
m.p. = 72oC
2,3,4,6-Tetra-O-methyl-D-galactose + O
CH2OH
OMe
MeO HO B OH
Cool, concentrate
Dil H2SO4
14 hrs, 100o,
neutralize
A syrup +
2,3-Di-O-methyl-D-mannose O
CH2OMe
OMe HO C
MeO OH
A syrup
2,3,6-Tri-O-methyl-D-mannose

15. Methylation Analysis III
MeO O
CH2OMe
OMe A OH O
CH2OH
OMe
MeO HO B OH O
CH2OMe
OMe HO C
MeO OH + +
2,3-Di-O-methyl-D-mannose
2,3,6-Tri-O-methyl-
D-mannose
2,3,4,6-Tetra-O-methyl-
D-galactose
1. NaBH4 reduction
2. Acetylation
CH2OAc
CH2OMe C
OAc
OMe
MeO A
<
CH2OAc C
OAc
MeO B
<
CH2OAc
CH2OMe C
OAc
MeO
< + +
Note, “Ac” = CH3C- =O
Note, “Me” = CH3
Partially methylated alditol acetates

16. Methylation Analysis IV Possible Structures (shorthand)
4)Man(1
Gal 1 6 A
6)Man(1
4)Man(1
Gal 1 4 A 1 2 B C B C
Gal 1 4
Man 6
4)Man(1 3 A
Gal 1 4
Man
6)Man(1 A C C B B

17. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Linkage types/ring sizes
Monosaccharide sequence

18. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Linkage type
Monosaccharide sequence
Linkage configuration

19. Polysaccharide Structure
Structural Analysis(generalities)
Sugar residues
Linkage type
Monosaccharide sequence
Linkage configuration
DP/MW/Higher Orders of Structure

22. H2O
H+ bond w/in chain
H+ bond
between chains
H2O
K+ ion ligands
(6 each)