* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Protein stability
Survey
Document related concepts
Phosphorylation wikipedia , lookup
Signal transduction wikipedia , lookup
Magnesium transporter wikipedia , lookup
G protein–coupled receptor wikipedia , lookup
Protein design wikipedia , lookup
List of types of proteins wikipedia , lookup
Homology modeling wikipedia , lookup
Protein (nutrient) wikipedia , lookup
Protein phosphorylation wikipedia , lookup
Protein moonlighting wikipedia , lookup
Protein domain wikipedia , lookup
Intrinsically disordered proteins wikipedia , lookup
Protein structure prediction wikipedia , lookup
Protein folding wikipedia , lookup
Protein purification wikipedia , lookup
Nuclear magnetic resonance spectroscopy of proteins wikipedia , lookup
Transcript
11-1 Protein stability, protein-protein interactions Protein stability - how proteins achieve stability under extreme conditions (class presentation) Protein-protein interactions - recent literature (presentations) Stabilization/destabilization forces affecting proteins Any of the forces/structures below could be stabilizing or destabilizing: hydrophobic…………… increased strength at higher temperatures H-bond…………………. mostly stabilizing; could decrease flexibility ionic…………………….. can be attractive or repulsive surface residues………. major contribution to protein stability internal residues………. major contribution to protein stability compactness………….. can affect stability or flexibility loops…………………….short loops increases stability at higher temperatures cavities…………………. presence and size can affect stability secondary structures…. e.g., β-sheets, α-helices more stable than coils quaternary structures… oligomeric structures can be more stable (esp. hetero.) ligand binding…………. e.g., nucleotides, cofactors, etc. membrane binding…… major effect(s) on protein stability protein modifications…. modulation of conformation, activity, stability, location others…………………... temperature, pH, salt, small molecules, pressure, etc. 11-2 11-3 Protein stability in different organisms Terminology psychrophile ..... cold-adapted; cold-loving (-2 ºC to ~15ºC) mesophile ..... grows at moderate temperatures (~15ºC to ~45ºC) and conditions thermophile ..... heat-loving; grows at >45ºC up to ~80ºC hyperthermophile ..... grows at >80ºC; limit so far is about 115ºC halophile ..... grows at high in concentrated salts (internal >1M!) acidophile ..... grows under highly acidic conditions, i. e., ~ pH 0-pH 2) barophile ..... adapted to high pressures (e.g., underwater) extremophiles ..... those that grow under extreme conditions Surface residues: stability vs instability thermophilic thermophilic CspB - Mesophilic Bs-CspB and thermophilic Bc-Csp differ at 12 positions in 67 aa - variants at all positions were constructed and tested for stability Cold shock protein (Csp) from Bacillus caldolyticus. Perl et al. (2000) Nat. Struct. Biol. 7, 380. mesophilic CspB increased stability thermophilic mesophilic decreased stability 11-4 Protein biogenesis/degradation machineries in extremophiles 11-5 Question: how do organisms survive at extreme temperatures? Do they have more proteins devoted to protecting the organism, e.g., molecular chaperones? protein folding catalysts? proteases? Answer: the short answer is ‘it doesn’t appear to be the case’ intrinsic property of proteins 11-6 protein-protein interactions “Here one should remember that any protein fails to execute its function unless it interacts with other biomolecules” - Takashi et al. (2001) Proc. Natl. Acad. Sci. USA 98, 4569.