lec 27 - Lecture 27 Regulation of protein function(Ch 3 p...

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Lecture 27: Regulation of protein function (Ch. 3; p. 88-92) Regulation by changes in conformation: Allostery + cooperativity Common regulators: Calcium GTP Phosphorylation/dephosphorylation
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“Allos” – other “Stereos” – solid/3 dimension Allostery Binding of one ligand influences binding of another ligand in a different region of the protein !In fact, ligand interaction ALWAYS influences protein conformation to a certain extent!
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A A A B B B Allostery Positive: Change in conformation spreads throughout the protein
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A A B Allostery Negative: Change in conformation spreads throughout the protein B
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Consider a polypeptide as a network of interactions involving the covalent bonds of the backbone and all the non-covalent interactions between the various amino acids. Protein-protein binding (but also binding to other molecules) implies formation of new non-covalent bonds, which in turn will influence the overall “equilibrium” of interactions, and can thus in some cases propagate changes throughout the whole protein. Here comes a simplified model (imaginary example) to help you visualize this concept. Allostery
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Allostery
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Allostery
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Allostery
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Allostery
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Allostery
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Allostery
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Cooperativity B A A B B A B A B A B A Binding of the 1st A induces changes in conformation that influence binding of B, but alters the conformation of the second subunit, favoring binding of the 2 nd A 1 st binding difficult 2 nd binding easy Regulation of multimers much more efficient ! Cooperativity can also be negative!
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monomer dimer tetramer 10% 90% Enzyme activity
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This note was uploaded on 12/07/2010 for the course BIO BIOL 200 taught by Professor Frogatto during the Fall '10 term at McGill.

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lec 27 - Lecture 27 Regulation of protein function(Ch 3 p...

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