Glycoconjugates Flashcards
what is the structure of Proteoglycans
one or more glycosaminoglycan chains are joined covalently to a membrane protein or a secreted protein
how is the glycosaminoglycan connected to the core protein in proteoglycans
by Tetrasaccharide bridges
what are proteoglycan aggregates
enormous supramolecular assemblies of many core proteins all bound to a single molecule of hyaluronate
what glycosaminoglycans does aggrecan carry
chondroidin sulfate and keratan sulfate chains
what are proteoglycans major components of and how does it provide strength and resilience
connective tissue such as cartilage
through their many noncovalent interactions with other proteoglycans, proteins, and glycosaminoglycans
how do glycoproteins differ from proteoglycans
its carbohydrate moieties are smaller and more structurally diverse than the glycosaminoglycans of proteoglycans i.e. no repetitive structures
describe the structure of a glycoprotein
The carbohydrate is attached at its anomeric carbon through a glycosidic link to the OOH of a Ser or Thr residue (O-linked), or through an N-glycosyl link to the amide nitrogen of an Asn residue (N-linked).
glycoprteins are usually
a) negative charged
b) neutral
c) positive
neutral
what might change the protein polarity and solubility of glycoproteins
Carbohydrate fraction protecting it from proteolysis
what do glycoproteins play a role in
- Membrane, intracellular displacement, orientation and secretion
- Embryonic development and differentiation
- Metastasis in cancer cells
what do the hydrophilic clusters of carbohydrate on glycoprotein do
alter the polarity and solubility of the proteins with which they are conjugated
what are examples of glycoproteins
- Immunoglobulins (antibodies
- Follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone
- Lactalbumin
what is the dominant surface feature of the outer membrane of gram-negative bacteria and give examples of these bacteria
Lipopolysaccharides
for example
Escherichia coli and Salmonella typhimurium
The cholera toxin molecule (produced by Vibrio cholerae) triggers _______ after entering _________ responsible for ___________ from the intestine. The toxin attaches to its target cell through the ___________________________, a membrane phospholipid, on the surface of intestinal epithelial cells
diarrhea
intestinal cells
water absorption
oligosaccharide of ganglioside GM1
The pertussis toxin produced by ______________, the bacterium that causes ________________, enters target cells only after interacting with an ______________ with a terminal ___________ residue
Bordetella pertussis
whooping cough
oligosaccharide
sialic acid
