INTRODUCTION TO GLYCOCONJUGATES
PPT Slide
Appreciation of fermentation is as old as civilized man himself
ANIMAL AND PLANT GLYCOPROTEINS SHOW VARIOUS SUGAR CONTENTS
Oligosaccharides of the cell surface are attached to membrane embedded proteins and certain lipid molecules
GLYCOCONJUGATES
New methods revolutionised the study of glycoconjugate structures
Glycoproteins are found responsible for
STUDYING GLYCOCONJUGATES
ALDOSE: CH2(OH)(CHOH)n-2HCO KETOSE: CH2(OH)(CHOH)n-3COCH2OH
Glycosidic link
Potential diversity of oligosaccharide structures is enormous
Comparable sequences of oligopeptide and oligosaccharide differ drammatically in isomeric possibilities
Repertoire of monosaccharides found in glycoconjugates is limited
Oligosaccharides are linked to proteins by O- or N-glycosidic bonds
Acidic glycolipids
Central “dogma” of molecular biology
HETEROGENEITY OF CONJUGATED GLYCANS
BIOSYNTHESIS OF GLYCOPROTEINS STARTS IN ER
N-LINKED OLIGOSACHARIDES OF GLYCOPROTEINS
Common precursor of all N-linked oligosaccharides is Glc3Man9GlcNAc2.
Trimming of glucose in ER. Deglucosylation signals the export to Golgi Specific processing starts with demannosylation. Elongations and elaborations proceed stepvise.
Lectin-like chaperons mediate and control proper protein folding
Sequential development and changing importance of different functions of protein-linked oligosaccharides
O-LINKED SUGARS “Varietas delectat”
PROTEOGLYCAN STRUCTURE OF BOVINE CARTILAGE
STICKY JOBS OF PROTEOGLYCANS
Repeating disaccharide unit of antifreeze glycoprotein
GLYCOSYL PHOSPHATIDYLINOSITOL ANCHORS
GPI anchors appear ubiquitously on the surface of eukaryotes
Biosynthesis of GPI anchors
FUNCTION OF OLIGOSACCHARIDES BOUND TO PROTEINS MAY BE
NON-SPECIFIC ROLES OF GLYCANS BOUND TO PROTEIN
O-linked saccharides extend functional protein domains above membrane surface
Different lectins specifically recognise distinct oligosaccharide structures
LECTIN MEDIATED INTERACTIONS
Mannose binding protein - innate protective immunity against pathogens by discrimination of self-nonself
MAJOR FAMILIES OF ANIMAL LECTINS
COMBATTING INFECTION
EVOLVING FUNCTIONS OF OLIGOSACCHARIDES
?-D-glucosidase inhibitors - potential antiviral agents
C-mannosylation of tryptophan in human Ribonuclease 2
Carbohydrate content of MUC1 is decreased in tumor cells
Stress causes specific changes of protein glycosylation in human serum
Concluding remarques
Concluding remarques cont.
Email: iletunic@mb1.pharma.hr
Home Page: http://mb1.pharma.hr/bmb
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