Protein structure and folding Part 2 Flashcards
Which arrangement of globular protein may or may not independently stable and has a recognizable folding pattern/ particular arrangement
Motif
Which arrangement of globular protein is independtly stable?
Domain
How do we determine protein structure
- Xray crystallography
- NMR
What are pros of X-ray crystallography
no size limit, well stablished
Pros of NMR
no need to crystallize
see many hydrogens
protein in solution (more natural)
Cons of X-ray crystallography
difficult for membrane protein
cannot see hydrogens
Cons of NMR
works best for small protein
difficult fot insoluble protein
Motif equals
structure
If a particular arrangement is related to some function, it is a
domain
Domain equals
function
All protein begins life on ribosomes in what state
unfolded or non-native state
What dirves protein to go from Non-native to native state
- Hydrophobic effect
- Maximization of H-bond and stavilizing ion pair
What drives protein folding
increase in entropy fo water
The hydrophilic sheels of globular protein are stabilized by
hydrogen bond, sulfide bond and salt bridges
Loss of structural integrity with accompany loss of activity is called
Denaturation
Protein can be denatured by
heat or cold
pH extremes
organic solvents
chaotropic agents
What are chaotropic agent
urea, guanidinium hydrochloride (GdnHCl)
Main takeaway from Christian Anfinsen experiment
the cow stomach has Ribonuclease A which digest RNA in food. It is a very stable protein because it is in digestive tract of pH 4
β mercaptoethanol and Urea will denature and reduce protein
protein always fold simultaneously into native struture
8 cysteines can form how many disulfide bonds
4
What structure does disulfide bond stabilize
tertiary structure
What is the function of β mercaptoethanol
reducing agent of disulfide bond
What is the function of urea
denature protein
Do disulfide influence/promote folding?
no, they stabilize native state
why is native state thermodynamically favorable
weak interactions are maximized and most protein do not have disulfide bond. These add up and stabilize protein
