L7: Protein Folding II Flashcards
prediction of 2ndary structure
using the chou-fasman method
empirical technique for prediction of 2ndary structures
protein tertiary structure
spatial arrangement of aa residues that are far apart in the sequence and to the pattern of disulfide bonds
quaternary structure
spatial arrangement of subunits and nature of their interaction
protein denaturation
unfolding is an all or nothing process
partial loss of structure destabilizes the remainder of the structure
PDI
protein disulfide isomerase
rearranges the polypeptide’s non-native S-S bonds
protein turnover
lifespan of proteins is highly regulated
PPI
peptidyl prolyl cis-trans isomerases
HSP 70 and 40
ATP-driven
functions: reverse misfolded proteins
unfold/refold proteins
mitochondria contain their own Hsp proteins
60 and 70
are distinct from the heat shock proteins of the cytosol
conditions for protein denaturation
heat
extreme pH’s
agitation
chemicals for protein denaturation
detergents ex. SDS
chaotropic agents
organic solvents
methods of analysis of protein denaturation
turbidity circular dichroism uv absorption fluorescence biological acitivty
define molecular chaperons
essential proteins that bind to unfolded and partially folded polypeptide chains
functions of molecular chaperons
prevent improper association of exposed hydrophobic segments of misfolded proteins
allow misfolded proteins to refold or be destroyed
what are co-chaperons?
binds to molecular chaperons to activate them
what are co-chaperons?
binds to molecular chaperons to activate them
Hsp90 family
integrates signaling functions, acting at a late stage of folding of substrates
chaperonins
a protein folding container
hsp60, 10
barrel analogy from bittel
*ATP to take top on/off
short lived proteins are mostly associated w/ ?
metabolic functions
the proteasome
a protein degradation machinery
large protease complex which digest ubiquinated proteins
26S proteasome is made of
2 19S regulatory units –exit/entry channels
20S catalytic core
functions of 19S
recognizes ubiquintaed proteins
isopeptidase cleaves signal off
protein directed inwards to 20S
20S segment
composed of 28 subunits
access controlled by 19S
proteasome generates free amino acids
degrades proteins into peptide fragments which can be further digested to yield free amino acids
