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27 Cards in this Set
- Front
- Back
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Where do antigens bind to antibodies?
What is this area made of? |
N-terminus where the there are hypervariable loops (VL and VH)
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What holds the chains together in an antibody?
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disulfide bonds
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what is a sequence on an antigen that the antibody recognizes called?
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epitope
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what kind of antibody recognizes only ONE epitope?
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monoclonal antibodies only recognize one epitope on an antigen - they are more specific than polyclonal antibodies.
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what are folds in immunoglobulin chains called?
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immunoglobulin domains
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what are 6 steps in intracellular maturation of collagen?
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1. synthesis of pro-a-chain
2. hydroxylation of proline/lysine 3. glycosylation of hydroxylysines 4. self assembly of 3 pro-a-chains 5. procollagen 3 helix formation 6. secretion from secretory vesicle |
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which steps in intracellular maturation of collagen occur in the ER and Golgi compartments?
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1. synth of pro-a-chains
2. hydroxylation 3. glycosylation 4. self-assembly of 3 pro-a-chains |
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are helices in tropocollagen alpha-helices?
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no tropocollagen does not make alpha-helices
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What is notable about primary structure of tropocollagen?
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q 3rd residue is a GLYCINE
it is also PROLINE rich. |
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What is useful in having tropocollagen be "proline rich"?
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N-C(alpha) bonds are locked - so this limits rotation and favors helical shape.
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What stabilizes the primary structure of tropocollagen?
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H-bonds
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What rxn occurs when prolyl residue is hydroxylated?
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prolyl residue + O2 + aKG (PROLYL-4-MONOOXYGENASE)---> 4-hydroxylprolyl + CO2 + Succinate
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why does the hydroxylation rxn require aKG involvement?
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the enzyme catalyzing this rxn is a monooxygenase - these require a second reducing agent, like aKG.
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What cofactors are used to make the hydroxylation of proline and lysine go?
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Fe and Vit C (Ascorbate)
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What enzyme catalyzes the hydroxylation of lysine?
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lysyl-5-monooxygenase
deficiency of this causes Ehlers-Danlos Syndrome IV |
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What rxn needs Vitamin C in the intracellular maturation of collagen?
What other cofactor does it need? Deficiency in Vit C causes what dz? |
The hydroxylation of prolyl residues.
Fe. Scurvy - gum degeneration, skin lesions, blood v fragility, anemia |
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what is different about pro-alpha1 and pro-alpha2 from the rest of the tropocollagen structurally?
What step are we considering? |
these "pro" collagen areas do NOT have glycine q3rd position and are NOT proline rich.
Formation of procollagen |
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What is the key step in formation of procollagen?
What step comes right before formation of procollagen? |
Key step is the oxidation of cysteine into cystine. (***an important general mechanism for joining polypeptide chains).
Right after glycosylation. (Which occurs right after the hydroxylation of prolyl/lysine residues). |
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What happens after procollagen is made?
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Procollagen is SOLUBLE and is secreted into extracellular space by fibroblasts. Then proteolytic enzymes snip off the pro-alpha1/2 chains. Then SELF-ASSEMBLY occurs.
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What enzyme is responsible for the rxn which matures the collagen fiber?
What two conditions occur bc of deficiency of this? |
lysyl oxidase
lathyrism = after eating sweet peas that degrade this enz or Ehlers-Danlos Sydrome IX |
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Describe the lysyl oxidase rxn.
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5-hydroxylysyl residue(LYSYL OXIDASE+H2O+O2)--->
5-hydroxyallysyl residue + H2O2 + NH4+ |
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What is special about the product in the lysyl oxidase rxn? What is the product?
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Product = 5-hydroxyallysyl residue
This residue has a new aldehyde group which is VERY reactive and makes RIGID cross-links bt collagen fibers. |
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What causes Type IX Ehler's Danlos syndrome?
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low lysyl oxidase activity = NO MATURATION OF COLLAGEN FIBERS.
5-hydroxyallysl residue is not made. |
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What causes type VI Ehlers-Danlos syndrome?
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deficiency in lysyl-5-monooxygenase.
This is part of the hydroxylation rxn in step 2 of the maturation of tropocollagen. Glycosylation won't occur and procollagen won't form. |
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What causes type VII of Ehlers-Danlos syndrome?
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low/no procollagen aminopeptidase (recessive) or mutations in the alpha2(I) gene.
Procollagen won't lose the pro-alpha tails - so NO SELF ASSEMBLY of tropocollagen fibers into collagen. |
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What bacteria causes gas-gangrene?
Why? |
Clostridium Hystolyticum.
It secretes collagenase. |
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What normal biological function uses collagenase?
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The post partum uterus uses collagenase to deconstruct the structures of pregnancy.
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