Slides 7 020212(2)

Slides 7 020212(2) - Lecture overview We are now discussing...

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Unformatted text preview: Lecture overview We are now discussing features of protein function Last lecture: Protein binding: how proteins interact with other molecules and other proteins to enable function Example: transport of oxygen by hemoglobin-Enzymes: Proteins as reaction catalysts (cooperativity)-Enzyme kinetics-Enzyme regulation Today! Question of the day: why does a goose breast look so different from a chicken breast? Hint: the dark red is heme, but not in hemoglobin, Rather cytochromes that are mitochondrial localized Goose breast Chicken breast http://www.levanacooks.com/balsami-roasted-chicken-breasts/ Question of the day: why does a goose breast look so different from a chicken breast? Hint: the dark red is heme, but not in hemoglobin, Rather cytochromes that are mitochondrial localized Goose breast Chicken breast http://www.levanacooks.com/balsami-roasted-chicken-breasts/ http://www.slashfood.com/2010/03/24/sliced-goose-breast-feast-your-eyes/ Today: Enzyme regulation 1) Inhibition of enzymes (kinetic analysis) I have posted a practice exam and key on Blackboard I will hold a recitation in preparation for the exam on Tuesday, Feb. 7 here in Leidy 10, 7:00-8:00 PM 2) Enzyme isoforms with differing properties 3) Enzyme complexes and local effects 4) Feedback inhibition Note: you can supplement reading for this lecture by pp. 194-205 and 220-228 In Lehninger, Principles of Biochemistry, 5th ed. the pdf’s are posted on Bb!! 5) Allosteric enzymes and activators/inhibitors 6) Enzyme regulation by covalent modification 7) Regulation by proteolytic cleavage 1a) Bisubstrate reactions Focus on glycolysis (enzymes) Figure 2-88 Molecular Biology of the Cell (© Garland Science 2008) Hexokinase Phosphofructokinase Pyruvate Δ G in cell All enzymes In between (estimates) (kJ/mol)-27.2-25.9-13.9 All near 0 (slightly<0) Voet and Voet p. 625 These three enzymes are highly regulated! Key regulatory points Figure 2-88 Molecular Biology of the Cell (© Garland Science 2008) Hexokinase Phosphofructokinase Pyruvate dehydrogenase All enzymes In between Captures Gateway to glycolysis Branchpoint All near 0 (slightly<0) Voet and Voet p. 625 These three enzymes are highly regulated! glucose at end Key regulatory points Hexokinase Phosphofructokinase All enzymes In between Captures Gateway to glycolysis Branchpoint All near 0 (slightly<0) glucose at end Pyruvate dehydrogenase Respiration Fermentation (responds to need) How much goes in Draws out product Keeps running at −Δ G Enzyme inhibition Many drugs function by enzyme inhibition Adderall Inhibits dopamine transporter (blocks reuptake from synapses) HIV protease inhibitor (shown bound in Active site of Pde-5) Inhibits Pde-5 (Stabilizes cGMP) Acetonephren (Advil) Inhibits Cox-2 (slows inflamation pathway) Inhibits viral multiplicaton Competitive inhibition Binds into active site: reduces ability of substrate to bind (increases K m ) Uncompetitive inhibition Binds to enzyme-substrate complex: lowers rate of catalysis Mixed inhibition...
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This note was uploaded on 03/07/2012 for the course BIOL 212 taught by Professor Kina during the Spring '12 term at UPenn.

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Slides 7 020212(2) - Lecture overview We are now discussing...

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