Glycosciences: Glycobiology & Glycochemistry e-learning course
What sort of Science is
Glycoscience?
(Introductory lecture)
Paula Videira
Faculdade de Ciências Médicas
Nova University, Lisbon Portugal
Glycosciences: Glycobiology & Glycochemistry
Glycoscience is the study of structure and
function of carbohydrates — biological
sugars
Glycobiology and Glycochemistry are two
main subareas
Glycosciences: Glycobiology & Glycochemistry
More complex deffinition for
Glycosciences
• The study of the structure, biosynthesis,
biology, and evolution of saccharides (sugar
chains or glycans) that are widely distributed
in nature, and the proteins that recognize
them.
• The branch of science concerned with the
role of sugars in biological systems.
Glycosciences: Glycobiology & Glycochemistry
DNA RNA PROTEINS
PHYSICAL ENVIRONMENT
ENZYMES
MICROBESPARASITES
GLYCOPROTEINSPROTEOGLYCANS
GLYCOLIPIDS
GLYCANS
ORGANISM
MATRIXCELL
TISSUES & ORGANS
DNA
SIGNALLINGMOLECULES
REGULATORYFACTORS DIET
LIPIDS
DNA
Glycan: A generic term for any sugar or assembly of sugars, in free form or
attached to another molecule = +/- saccharide or carbohydrate
Glycans cover the surface of all eukaryotic cells, all
prokaryotic cells and many viruses
Schematic representation of the
Thy-1 glycoprotein
glycosylphosphatidylinositol
GLYCANS CAN CONSTITUTE A MAJOR PORTION OF THE MASS OF
A GLYCOCONJUGATE
Glycoconjugate: A molecule in which one or more glycan units are covalently linked to
a noncarbohydrate entity
Glycosciences: Glycobiology & Glycochemistry
SURFACE GLYCOSYLATION IS UNIVERSAL IN LIVING ORGANISMS
• Every free-living cell and every cell within multi-cellular organisms are
covered with dense & complex layer of glycans.
• Even enveloped viruses that bud from surfaces of infected cells carry
with them the glycosylation patterns of the host cell.
• Most secreted molecules are glycosylated, and extracellular matrices of
multicellular organisms are rich in glycans
• Biofilms/ matrices secreted by unicellular organisms also contain
glycans.
• Reasons for apparent universality of cell-surface and secreted
glycosylation not clear.
• Apparently, evolution selected for glycans as being the most diverse
and flexible molecules for the interface between cells and the
extracellular milieu.
Glycosciences: Glycobiology & Glycochemistry
Basic concepts
• Glycan: generic term for any sugar or assembly of sugars (free form or attached to another molecule). May be used interchangeably with saccharide or carbohydrate.
• Glycoconjugate: A molecule in which one or more glycan units are covalently linked to a noncarbohydrate entity (protein or lipid).
• Carbohydrate: more generic term which includes monosaccharides, oligosaccharides, and polysaccharides as well as derivatives of these compounds
Common monosaccharides found in vertebrates
Basic glycobiology concepts
Monosaccharide symbol set b
c
Symbol nomenclature for structural depictions
Basic glycobiology concepts
Key:Gal GlcNAcFucNeuAc GalNAcGlc Man
N-Linked O-Linked
NeuAcαααα2-6Galββββ1-4GlcNAcββββ1-2Manαααα1
NeuAcαααα2-6Galββββ1-4GlcNAcββββ1-2Manαααα1
Manββββ1-4GlcNAcββββ1-4GlcNac-Asn6
3
6
Fucαααα1NeuAc αααα2-3Gal ββββ1-4GlcNAc ββββ1
NeuAc αααα2-3Gal ββββ1
GalNAc αααα-Thr6
3
αααα3
αααα6ββββ4β4β4β4β4
αααα6αααα6 ββββ4 ββββ2
αααα6 ββββ4 ββββ2
αααα3
αααα3
β4β4β4β4 β6β6β6β6
ββββ3
STANDARD SYMBOLS FOR GLYCAN STRUCTURES
Common classes of animal glycansGeneral pathways for biosynthesis
phosphatidylinositol
phosphoethanolamine
Initiation and maturation of the major types of eukaryotic
glycoconjugates in relation to subcellular trafficking in the ER-Golgi–
plasma membrane pathway
General pathways for biosynthesis
General pathways for biosynthesis
Vaccination with Theratope® (STn-KLH) as treatment for breast cancer
Leona A Holmberg, Brenda M Sandmaier
< Sialyl-Tn is a carbohydrate associated with MUC1. It is a unique tumor-associated antigen, present on
many adenocarcinomas including breast, ovarian, colorectal, gastric and pancreatic. Consequently, Sialyl-
TN is an ideal candidate for boosting the patient’s immune system specifically against a unique tumor-
associated antigen. The cancer vaccine Theratope® was developed by Biomira, Inc. using a synthetic
Sialyl-Tn antigen that emulates the unique carbohydrate on human cancer. Clinical trials have
predominately been carried out in breast cancer patients and these trials are outlined in this profile.
The A, B, and H blood group antigens are glycans presented on the type-1 or type-2 N-
acetyllactosamines, on O-GalNAc glycans (type-3), or on glycolipids (type-4).
Glycosciences: Glycobiology & Glycochemistry
GENERAL PRINCIPLES
how do we get the sugars?
• Glucose and fructose are major carbon and energy
sources for most organisms as yeast and humans.
• Most organisms can derive monosaccharides needed
for glycan biosynthesis from these sources.
• Not all of these biosynthetic pathways are equally
active in all types of cells.
Biosynthesis and heterogeneity
Nucleotide-Sugar + HO-Acceptor
Sugar-O-Acceptor(Product)
Nucleotide
Glycosyltransferase
Generalized Glycosyltransferase
Reaction
Biosynthesis and heterogeneity
Glycosciences: Glycobiology & Glycochemistry
Most glycosylation reactions use activated sugar donors
Biosynthesis and heterogeneity
Biosynthesis and interconversion of monosaccharides
Biosynthesis and heterogeneity
Glycosciences: Glycobiology & Glycochemistry e-learning course
Glycosylation Reactions
Biosynthesis and heterogeneity
Glycosyltransferases
GlycosyltransferaseFamily
DonorSubstrates
# Genes(min)
Fucosyl- GDP-Fucose 11
Sialyl- CMP-NeuAc 20
Galactosyl- UDP-Gal 19
N-Acetylglucosaminyl- UDP-GlcNAc 34
N-Acetylgalactosaminyl- UDP-GalNAc 30
Mannosyl- GDP-Man 13
Glucosyl- UDP-Glc 8
Biosynthesis and heterogeneity
잠;
The Big PictureBiosynthesis
Glycan
Function
Transferases &
Hydrolases
Glycan-Binding Proteins
(Lectins)
잠;
Thank you!
Top Related