Complex Carbohydrates Flashcards
Hyaluronic acid
GAG repeat units, negative charges from sulfate group. One sugar always an amino acid, but is acetylated so no positive charge
Glucosaminoglycans
Polymers of (-) charged disaccharide repeat units Ex: heparin and hyaluronic acid
Proteoglycans
(-) charged GAG chains linked to a core protein to give a proteoglycan monomer
Many monomers associated with long hyaluronic acid chain to form proteoglycan aggregates
Properties/functions: neg charges repel, slippery/slimy, good lubricant, shock absorber (synovial fluid), mostly on cell surface especially around connective tissues (cartilage, tendon, skin)
Heparin
A type of glycosoaminoglycan
Anticoagulant, prevents runaway clotting
Glycoproteins
Mostly protein, some ch2o
CH2O chains are zip codes that target glycoproteins to lysosomes and plasma membranes
Cell surface recognition and self vs. non-self recognition
Blood group antigens
Degradation of proteoglycans/GAGS
They turn over and must be replaced. Endocytosis and vesicle transport to lysosomes where degradation occurs through acid hydrolases
Genetic defects in lysosomal degradations possible and cascade big problems. Undegraded GAGS pile up in lysosomes and extracellularly
Sphingolipids or glycosphingolipids
Similar structure to phospholipids
Seen in the nervous system in neurons and myelin
Long hydrophobic tail, sphingosine, and a fatty acid tail
Function: structural components of membranes, specialized membrane domains, sources of smaller lipid signaling molecules
In blood elements
Sphingolipidoses
Genetic defects in catabolism (lysosomal storage disorders)
Sphingolipids are synthesized, do their business and are degraded
Catabolism involves hydrolytic degradation by catabolic enzymes
Inborn errors of metabolism–genetic mutation in enzymes, lipids upstream accumulate
Krabbes disease
KC
Cerebroside accumulation in myelinating cells. Alternative catabolism is toxic and kills cells–psychosine
X=H
Metachromatic Leukodystrophy (MLD)
MLDS
accumulation in sulfatide in myelinating cells
X=galactose-sulfate
Tay-Sachs Disease
TSG
Accumulation of gangliosides in neurons, cherry red spot in the retina
X=glucose, precursor to gangliosides
Ganglioside: exclusively on cell surface, especially neurons.
Niemann-Pick A&B
NPSphing
Accumulation of sphingomyelin
X=P-choline
Sphingomyelin seen in all cells, sphinolipid and phospholipid
Ceramide
Sphingosine plus a fatty acid, base of sphingolpids
Mucopolysaccharidoses
Defective catabolism of GAGS in lysosomes
Ex: Hunters and Hurlers syndromes
