PHRD5025 Biochem - Lecture 4 Protein Aggregation Diseases

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  1. 2 types of protein aggregates
    • 1) non-amyloid
    • 2) amyloid
  2. aggregate without cross-Image Upload structure

    ex: sickle cell anemia
  3. aggregate with cross-Image Upload structure

    ex: Alzheimer's, Parkinson's, cataracts
  4. cause of sickle cell disease
    single nucleotide change from GAG to GTG  at amino acid position 6 (E6V) in the Image Upload-chain of Hb

    (charged -> hydrophobic)
  5. Hb S
    • - sickle Hb - stick to one another forming long rod-like fibers
    • - 14 sickle Hb chains twine as an Image Upload-helical bundle
  6. structure of sickle cell aggregates
    Image Upload-helical structure
  7. most common cause of dementia in the elderly
    Alzheimer's disease
  8. deposits of beta-amyloid protein generated from Alzheimer amyloid precursor protein (APP) which accumulates in spaces between nerve cells
    amyloid plaques
  9. deposits of tau proteins involved in microtubule formation
    neurofibrillary tangles
  10. control motility/movement of brain cells
  11. location of APP gene
    chromosome 21
  12. kinetics of amyloid formation
    • 1) native protein unfolds -> hydrophobic residues exposed
    • 2) hydrophobic patches form circular aggregates (oligomers)
    • 3) oligomers stack & form protofibrils
    • 4) protofibrils twine around one another & form long amyloid fibrils
    • 5) fibrils precipitate -> amyloid plaques
  13. Image Upload-amyloid structure
    • - cross-Image Upload helical
    • - H-bonds between 2 Image Upload-strands from 2 stacked protein molecules
    • - H-bonds parallel to long axis
  14. 2 processes of amyloid growth
    • 1) nucleation (lag phase)
    • 2) propagation
  15. risk factors for AD
    • 1) old age
    • 2) alterations on chromosomes 1, 14, or 21
    • 3) head injury
    • 4) gender (more common in women)
  16. protein involved in Parkinson's disease
    Image Upload-synuclein -> becomes unfolded & forms amyloid-like filaments
  17. filamentous inclusions within dopaminergic neurons in Parkinson's disease
    Lewy Bodies
  18. inherited autosomal dominant progressive neurodegenerative disease characterized by chroeiform movements, psychiatric problems, and dementia
    Huntington's Disease
  19. peptide necessary for embryonic development, and helps with cell regulatory processes
    Huntingtin peptide
  20. important for diagnosis, disease onset, and severity determination in Huntington's disease
    number of CAG repeats in mutant Huntingtin
  21. what does Huntington's disease mainly attack?
    basal ganglia of the brain
  22. most probable protein at fault for Huntington's disease
    Rhes (guanine nucleotide binding protein selectively located in the striatum)
  23. neurodegenerative disease affecting nerve cells in the brain and spinal cord, resulting in progressive weakness of voluntary muscles and paralysis
    myotropic lateral sclerosis (ALS) or Lou Gehrig's disease
  24. homodimer that protects cells from superoxide toxicity by converting it to water
    superoxide dismutase 1 (SOD1)
  25. what does each subunit of SOD1 bind to?
    1 copper atom, 1 zinc atom
  26. mutations in this gene causes familial ALS
  27. type of aggregation that occurs in ALS
    aggregation of well-folded, structured proteins that clog other cytoplasmic components

    SOD1 mutations promote production of copper-deficient misfolded species
  28. PrPC
    • -normal prion protein
    • -rich in Image Upload-helices
  29. PrPSC
    • - conformationally changed prion protein
    • - rich in Image Upload-sheets
  30. what leads to prion disease
    aggregation of PrPSC
  31. types of prion diseases
    • - Creutzfeldt-Jakob Disease (CJD)
    • - Bovine Spongiform Encephalopathy (BSE/mad cow)
  32. types of CJD
    • 1) sporadic/spontaneouss
    • 2) familial/inherited defect in prion protein gene (Chr 20)
    • 3) acquired through contaminated meat
  33. cause of cataracts
    defective crystallin in the lens prevents the protein from acting as a chaperone, resulting in protein aggregates
  34. significant components of mature-onset cataracts
    D-crystallin and S-crystallin
  35. signs of cataracts
    • - inability to identify blues, purples, and greens
    • - blurred vision
    • - poor night vision
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PHRD5025 Biochem - Lecture 4 Protein Aggregation Diseases
2013-09-09 05:30:05
Protein Aggregation Diseases

Protein Aggregation Diseases
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