Lecture 2Slide 2Slide 3Slide 4TRANSITION STATE THEORYSlide 6Slide 7Slide 8Derivation of Michaelis-Menten equationSlide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Lecture 2•August 3, 2005•Lehninger (4th Edition), Chapter 6,ENZYME KINETICSLNC Chapter 6REACTANTSSUBSTRATESPRODUCTS kFirst order reactions: A P kSecond order reactions: A + B PA + A P1st order: ln[A] = ln[Ao] - kt or [A] = [Ao] exp(-kt) 2nd order: 1/[A] = 1/[Ao] + kttime[A]time[A]1timeln [A]TRANSITION STATE THEORYA CB DA CB DA CB DA catalyst serves in at least two ways:it binds and aligns the substratesit facilitates the redistribution of electrons (charges)k1k2E + S ES Products k-1CHAPTER 6Enzymes and Enzyme KineticsFig. 6-2Fig. 6-3Derivation of Michaelis-Mentenequation•1. equilibrium assumption: k-1 >> k2•2. steady state assumption: d[ES]/dt = 0•Note: [E] = [E]total – [ES]Hmmm..??when [S] >> Km then v vmax and vmax = k 2 [E] T k2 x [E]T x [S]v = ------------------------- Km + [S]k -1 + k 2 Km = k 1dKm Kd whenk -1 >> k 2Fig. 6-11Fig. 6-121 Km 1 1 = x +vo v max [S] v maxy = ax + bLineweaver-Burk PlotDouble Reciprocal Plotbox. 6-1- another definition: v max k2 = k cat = ------------ [E] T TURNOVER NUMBERmolecules of substrate / molecule of enzyme / secondmoles of substrate / mole of enzyme / secondReactions with more than one substrate(more typical)Overall reaction:S1 + S2 P1 + P2Fig. 6-13LNC 6-14 aLines intersect: ternary complex is formed in the reactionLNC 6-13 bThis case is also referred to as the Ping-Pongordouble displacement mechanismLNC 6-14 b Lines do not intersect: no ternary complex is formedEnzyme InhibitorsFig. 6-15aCompetitive Inhibition = 1 + [I] / KI box. 6-2.1Fig. 6-15bUncompetitive Inhibition’ = 1 + [I] / KIbox. 6-2.2Fig. 6-15cMixed InhibitionWhen = ’, then we also speak of noncompetitive inhibitionbox 6-2.3LNC 6-28FEEDBACK INHIBITIONLNC 6-26LNC 6-27ASPARTATE TRANSCARBAMYLASELNC 6-29aLNC 6-29bLNC 6-29cPart IIIBioenergetics and MetabolismChapter 13 in LNCTHE CARBON CYCLEureaTHE NITROGEN CYCLETypes of Organic Reactions1) Group transferGlucose + ATP Glu-6-P + ADPH2O + ATP Pi + ADP2) Oxidation-reduction reactionsEthanol + NAH+ acetaldehyde + NADH + H+3) Eliminations, isomerizations, rearrangementsaldose ketose4) reactions involving making or breaking of C-C bondsFru-1,6, bisphosphate dihydroxyacetone-phosphate + glyceraldehyde-3phosphate•End of Lecture 2•Aug. 3,
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