9-12-08_lecture_proteinID2

_lecture_prot - Poets say science takes away from the beauty of the stars mere globs of gas atoms I too can see the stars on a desert night and

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Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I, too, can see the stars on a desert night, and feel them. But do I see less or more?” - Richard Feynman “Marge: Homer! There's someone here who can help you. .. Homer: Is it Batman? Marge: No, he's a scientist. Homer: Batman's a scientist?! Marge: It's not Batman!”
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Announcements Quiz 2 due today at noon First exam – Next Friday, September 19 th Review questions will be given out this afternoon. They are for review and will not be graded or handed in. Answers will be given on Monday. Try them without answers first. Lecture today by Nobel laureate Philip Sharp on RNA. Lecture will be in Fowler Hall at 3:30.
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Schematic depiction of secondary structures showing tertiary structure of ribonuclease Alpha helix Beta sheet Cysteine disulfide bond Irregular structure, Loops and turns Irregular regions often sites of greatest biologic activity, Most flexible regions
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Example of distribution of hydrophilic and hydrophobic residues in cytochrome c. Green=hydrophilic, red=hydrophobic
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Hydropathy plots are used to identify membrane spanning regions of a protein Hydropathy plots show the amount of free energy required to move amino acids to an aqueous medium. Residues 74-93 are hydrophobic and likely to be membrane-spanning
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Domain shuffling: recycling on an evolutionary time scale Alberts et al. Molecular Biology of the Cell The same domains, such as the brown serine protease domains, are re-used in different cellular proteins, typically with the same functions across proteins. Modularity!
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A protein’s conformation is repeatable and arises as a consequence of finding the lowest energy configuration Don’t stress, relax! The ability to re-form in a functional manner is called self- assembly.
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Mystery meat: Methods for protein identification, sequencing and interactions
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Ion-exchange chromatography Use charged matrix to attract oppositely charged proteins Can vary pH of solvent to vary protein charge (Why?) Isoelectric point = the pH at which the protein is neutral (typically not pH=7) Can also have gel-filtration chromatography (by size)
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Affinity chromatography Useful if you have a known or desired target or ligand Only proteins that bind to the target will remain in the column Can dissociate bound protein by changing pH Depending on initial protein mixture, may get closely related proteins or multiple bound proteins
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How do you know you have the right protein? Enzyme assays.
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This note was uploaded on 02/09/2010 for the course BIOL 230 taught by Professor Bartlett,e during the Fall '08 term at Purdue University-West Lafayette.

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_lecture_prot - Poets say science takes away from the beauty of the stars mere globs of gas atoms I too can see the stars on a desert night and

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