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Lecture 5
Protein folding & function
| Question | Answer |
|---|---|
| tertiary and quaternary structures are determined by | primary structures; R-groups of AAs encoded by genome |
| T/F primary sequence has limited number of possible folding pathways | TRUE |
| What are the forces stabilizing protein structure? TEST | Hydrophobic effects H bonds Charge-charge interactions disulfide bonds metal ions (ex iron-heme group) |
| hetero vs homo dimer | protein with multiple different polypeptide subunit=hetero homo has same polypeptide subunit |
| denaturation is | protein unfolding, usually with loss of biological activity |
| why is there a loss of biological activity during denaturation | because denaturation involves disruption of non-covalent bonds and thus loss of secondary and tertiary structures |
| how does are primary structures of proteins conserved during denaturation? | denaturation is not strong enough to break the covalent peptide bonds, thus primary structure remains intact |
| types of denaturation? | Heat– disturb weak bonds& 2ndary structures pH–change ionization state of R-groups, disrupting 2ndary structure (revert back to primary) chemicals–detergents (SDS)&chaotropic agents (urea) allow H2O to enter hydrophobic areas and disrupt normal folding |
| what do reducing agents do? | break disulfide bonds (between cysteines) to get protein back to primary |
| what are some reducing agents? | DTT β-mercaptoethanol |
| difference between protein reduction and denaturation? | reduction breaks disulfide bonds denaturation breaks weak, noncovalent bonds |
| Anfinsen experiment? | Ribonuclease treated with chaotrope (urea) and reducing agent ( β-mercaptoethanol)--> lost enzyme activity when denatured ribonuclease was dialyzed to remove urea and β-mercaptoethanol--> protein renatured, restoring activity |
| protein folding happens in__________ with several __________ | endoplasmic reticulum intermediates |
| steps of protein structure | unfolded secondary structure domains molten globule native tertiary structure |
| is protein folding always facilitated by proteins? | in vivo, it is often facilitated by proteins can self assemble |
| what are chaperones | binding proteins (loose association, not permanent) which assist in the formation of stable 3D protein structures in protein folding, most require ATP, different physical structures |
| what do chaperon protein do with misfolded/unfolded proteins | - fix the misfiling (fold it correctly)+ take to destination - if cant help fix it, then take it to the "trash", degrades it |
| heat shock protein is an example of | clamp type chaperon protein |
| GroEL-GroES protein complex is an example of | chamber type chaperon protein |
| what do clamp type and chamber type proteins use to facilitate correct folding | bind to misfolded protein and use ATP hydrolysis to fold |
| why is vitamin C important? | because prolyl and lysl hydroxylase enzymes require Vitamin C as a coenzyme. Tendons can get "loose" as a result of scurvy |
| osteogenosis imperfecta | glass bone disease cause brittle, pliable bones due to mutations in collagen genes α1 or α2 chains of type I collagen |
| Ehlers-Danlos Syndrome | elastic skin/joints defect in collagen synthesis |
| how does a prion disease start | misfolded version of the protein PrPsc, which acts as an infectious particle, interacts with PrPc (normal, wild type) version of the protein making it convert into mutant form |
| what are some prion diseases | mad cow creutzefeldt-Jacob/kuru |
| what causes sickle cell? | point mutation that changes glutamate to valine negatively charged AA to hydrophobic neutral causes cell to take on a sickle shape - ruptures easily, can aggregate and clump |
Created by:
rusulali97
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