protein folding Flashcards
(32 cards)
the disruption of tertiary and secondary protein structure that leads to los of protein function
denaturation
increases the rate of molecular motion/vibration, causing disruption of H-bonds, leads to protein unfolding
heat/temperature
cause protonation/deprotonation of sidegroups, alters H-bonding and salt bridges
proteins become insoluble and precipitate out of solution as they reach their isoelectric points
strong acid/base, pH changes
explain how chaperones aid in protein folding
Hsp 70 attaches to polypeptide chain first
uses ATP
promotes first folding of the protein
Hsp 60 (GroEL) attracts partially folded peptide chain
GroES “lid” comes on top of Hsp 60 body to keep protein inside.
hydrolysis of ATP causes hydrophilic environment in chaperone
promotes folding of protein
interfere with hydrophobic interactions; substitute or interfere in H-bonding
alcohols
disrupt hydrophobic interactions, leading to protein unfolding
detergents
interfere with salt/bridges/charge interaction in proteins
can “extract” water molecules from protein surface leading to protein aggregation and precipitation
high salt concentration
eliminate disulfide bridges causing unfolding
reducing agents
disrupts weak forces that stabilize tertiary protein structure
mechanical stress
when do proteins start folding
as they are made during translation
protein folding is assisted by
chaperones
chaperones assist protein folding in two ways
preventing inappropriate protein-protein interactions
help folding occur rapidly and precisely
how does Hsp 60 attract partially folded protein
initial hydrophobic environment inside protein
explain protein degradation
ubiquitin is added to protein that needs degraded
E1 E2 E3 in that order are used to attach 3 more ubiquitin molecules
protein travels to proteasome where degradation to amino acids occurs
protein disease causing agents that are not commonly genetically related but are usually ingested
prions
three characteristics of fibrous proteins
typically contain high proportions of alpha helices and beta sheets
often have structural roles
water insoluble
three characteristics of collagen
part of connective tissue matrix
left handed helices twist to form right handed triple helix
impart special properties to structure
three amino acids common in collagen
glycine
proline
hydroxyproline
three similarities of hemoglobin and myoglobin
similar polypeptide tertiary structure
same heme group to bind oxygen
very similar functions
two big differences between hemoglobin and myoglobin
myoglobin is a monomer and hemoglobin is a tetramer
different physiological binding affinities for oxygen
three additional characteristics of myoglobin
8 alpha helices
found in skeletal and cardiac muscles
has higher affinity for oxygen than hemoglobin
three additional characteristics of hemoglobin
2 alpha and 2 beta helices
found in red blood cells
transport oxygen from lungs to tissues
cooperative oxygen binding
once alpha 1 helix accepts oxygen the other subunits will form the appropriate shape to accept oxygen
cooperative oxygen binding
what element is essential for oxygen binding
iron
