CHAPTER 24
Proteoglycans:
Biological Roles and Strategies for Isolation
and Determination of Their Glycan Constituents
N. K. KARAMANOS 1
1
Summary
This chapter addresses issues on a major glycoconjugate family, the proteoglycans with particular interest in their types, the structural diversity of carbohydrates and the structure-function relationship. Procedures to isolate proteoglycans and strategies to characterize the fine chemical structure of their glycan
moieties are also presented.
2
Glycoconjugates:
General Aspects on Structural Diversity and Importance
Glycoconjugate is a generic term given to describe macromolecules in which carbohydrates having either the mono-, oligo- or polysaccharide form are covalently
bound to polypeptides/proteins or lipids. They involve glycoproteins, e.g.,
enzymes, immunoglobulins, transport proteins and hormones, mucins or mucoproteins, peptidoglycans, which are mainly present in bacteria, glycolipids and
proteoglycans.
Carbohydrate chemistry and analysis has to address a major problem arising
from the great structural diversity of glycans. The heterogeneity in structure is
mainly due to the following five parameters:
- variable number of monosaccharides present in oligo- and polysaccharides
- the anomericity of glycosidic bond, a- or ~- form
- the position of the glycosidic linkage between the anomeric C-l and any of the
available -OH groups of the next monosaccharide
- the branching of the main chain with other sugars, and
- the substitution of -OH groups and amino groups with sulfate, phosphate or
acetyl groups.
This structural diversity has no counterpart in proteins and nucleic acids. For
example, four monosaccharides are able to form 36,000 tetra saccharides, whereas
four amino acids or nucleosides may form only 24 tetramers. This may well be
I Section of Organic Chemistry-Biochemistry and Natural Products, Department of Chemistry,
University of Patras, 26 11 0 Patras, Greece.
Proteoglycans:
Biological Roles and Strategies for Isolation
and Determination of Their Glycan Constituents
N. K. KARAMANOS 1
1
Summary
This chapter addresses issues on a major glycoconjugate family, the proteoglycans with particular interest in their types, the structural diversity of carbohydrates and the structure-function relationship. Procedures to isolate proteoglycans and strategies to characterize the fine chemical structure of their glycan
moieties are also presented.
2
Glycoconjugates:
General Aspects on Structural Diversity and Importance
Glycoconjugate is a generic term given to describe macromolecules in which carbohydrates having either the mono-, oligo- or polysaccharide form are covalently
bound to polypeptides/proteins or lipids. They involve glycoproteins, e.g.,
enzymes, immunoglobulins, transport proteins and hormones, mucins or mucoproteins, peptidoglycans, which are mainly present in bacteria, glycolipids and
proteoglycans.
Carbohydrate chemistry and analysis has to address a major problem arising
from the great structural diversity of glycans. The heterogeneity in structure is
mainly due to the following five parameters:
- variable number of monosaccharides present in oligo- and polysaccharides
- the anomericity of glycosidic bond, a- or ~- form
- the position of the glycosidic linkage between the anomeric C-l and any of the
available -OH groups of the next monosaccharide
- the branching of the main chain with other sugars, and
- the substitution of -OH groups and amino groups with sulfate, phosphate or
acetyl groups.
This structural diversity has no counterpart in proteins and nucleic acids. For
example, four monosaccharides are able to form 36,000 tetra saccharides, whereas
four amino acids or nucleosides may form only 24 tetramers. This may well be
I Section of Organic Chemistry-Biochemistry and Natural Products, Department of Chemistry,
University of Patras, 26 11 0 Patras, Greece.