Proteins Flashcards
What is Amyloidosis?
Protein Misfolding, sometimes to form prefibrils, which fail to degrade and accumulate, causing organ dysfunction - it is seen in many chronic diseases
How does Amyloidosis appear under light microscopy and polarized light?
Congo Red dye - light microscopy
apple-green birefringence - polarized light
Where is serum amyloid A seen?
chronic inflammation
AL type of amyloid protein with gamma or kappa light chains is seen in what disease?
Multiple myeloma
ATTR amyloid protein is seen where?
familial mutations
Abeta amyloid protein is seen in what disease?
Alzheimer’s
Abeta2M amyloid protein is seen in what?
chronic hemodiaylsis
What Prion protein is normaly found in the brain?
PrPc
Does normal prion protein PrPc have any B-sheet?
it has little to none
What type of bonds are used for primary structure?
peptide bonds (covalent)
What type of bonds are used for secondary structure?
hydrogen bonds
How are α-helix and β-sheets formed?
they are formed by hydrogen bonding between atoms of peptide bonds
Hydrogen bonds between atoms of peptide bonds are responsible for what structure?
α-helix
Hydrogen bonds between the atoms of peptide bonds of opposite chain are responsible for what structure?
β-sheets
What are bends and turns generally composed of?
Glycine and Proline
What are the two regular secondary structures?
a-helix and b-sheet
What are other secondary structures?
loops and coils
What do bends, loops, and turns so in secondary structures?
Reverse the direction of the polypeptide chain
In which structure(s) are disulfide bridges seen?
tertiary, quaternary
What assist in protein folding?
chaperones and chaperonins
binds to nascent polypeptide chain as its synthesis is being completed and prevents uncompleted chains from folding prematurely; they also help to unfold the protein before being inserted into membranes
hsp70
barrel shaped proteins which allow unfolded proteins and nascent proteins to enter and its hydrophobic interior repels water and serves as template for protein folding
hsp60
what does the cis-trans isomerase do?
it converts a trans peptide bond preceding a proline into the cis conformation, which is well suited for making hairpin turns
What does the protein disulfide isomerase do?
it breaks and reforms disulfide bonds between the SH groups of two cysteine residues in transient structures formed during the folding process.
What are proteins degraded by?
ubiquitin-proteasome degradation system
What is AB42?
a degradation product of amyloid precursor protein that leads to neuronal damage
