protein stability and function Flashcards
native state
original state of a protein required for their proper function
denatured protein
unfolded protein that looses its function, often irreversible
what dictates folding pattern and stability of a protein
non-covalent interactions
- hydrophobic effect locates non-polar amino acids in core of folded protein, polar amino acids face exterior and interact with H2O
van der Waals interaction
weak electrostatic attraction between atoms that are close but not covalently bonded
- random fluctuations in distribution of nucleus and electrons create short lived dipoles
free energy of interaction in van der Waals
- atoms too close together will repel
- atoms ideal distance close to each other will have best attraction
- atoms slightly further are less attracted
- force fades if atoms are not close enough
- weak interactions are only effective if many atoms are in close contact
H-bonds in stabilization of protein
form between donors and acceptors that line up in the folded protein
Ion pairs in stabilization of protein
strong electrostatic interactions negative and positive side chains that pair up when nearby in the folded protein - SALT BRIDGE
Polar interactions important for maintaining structure
usually in the protein interior even tho most polar atoms are on the exterior
- since charged and H-bonding AAs will interact with environment
disulfide bonds
form when pairs of Cys-SH groups react with O2, releasing H2O
- makes strong covalent bonds
- few proteins have disulphide bonds
true or false - the primary structure contains all the information needed for the secondary and tertiary structure
true
how is ribonuclease denatures
it is placed in urea which weakens hydrophobic effect allowing protein to unfold
how does ribonuclease refold when urea is removed
after urea is removed expose to O2 so disulphide bonds form
- if exposed to O2 before refolding, disulfides pair up randomly and protein folds wrong - INACTIVE
