protein dynamics and folding Flashcards
what are the 3 factors that protein stability depends on the balance of?
1.unfavorable conformational entropy change-> folding 2.favorable enthalpy from intramolecular noncovalent interactions 3.favorable entropy from burying hydrophobic residues in water
what AAs are polar?
serine, threonine, asparagine, glutamine
what AAs are charged?
aspartate, glutamate, arginine, lysine, histidine
what AAs are nonpolar?
alanine, valine, leucine, isoleucine, methionine, tryptophan, phenylalanine
what is true about van der Waals interactions?
operate over short distances, result from the overlap of short-lived, highly fluctuating dipoles of nonbonding electron orbitals
what contributes to the stability of a folded protein?
numerous van der Waals interaction sum up
what offsets the contribution of noncovalent interactions, particularly hydrogen bonding, to enthalpy of folding?
protein folding decreases interactions between the protein and water
what is true about hydrogen bonding in protein folding?
it is NOT a driving force for protein folding because H-bonds with water are broken to make intramolecular H-bonds
H-bonding changes do not affect free energy much because…
formation of extended H-bond networds compensate for loss of AA-water bonds
what is a major contributor to protein folding and stability?
hydrophobic interactions (water around unfolded protein is ordered and structured)
what do proteins fold with?
hydrophobic residues on the interior
what does protein folding increase?
entropy of the protein-water system because water is less ordered
How can a protein structure be stabilized once a protein folds?
the formation of disulfide bonds between sulfhydryls (-SH) of cysteine
how can proteins be denatured or unfolded?
addition of organic solvents, urea, detergents, or heat
what is renaturation?
some proteins can spontaneously refold into native 3D structure
