Sinh học - Chapter 6: Mechanisms of enzyme actionTrypsin, chymotrypsin, elastase, thrombin, subtilisin, plasmin, TPA All involve a serine in catalysis - thus the name Ser is part of a "catalytic triad" of Ser, His, Asp (show over head) Serine proteases are homologous, but locations of the three crucial residues differ somewhat Substrate specificity determined by binding pocket
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Sinh học - Chapter 5 (part 2): Enzyme kineticsSome enzyme catalyzed rxns show more complex behavior E + S<->ES<->EZ<->EP<-> E + P With M-M can look only at rate limiting step Often more than one substrate E+S1<->ES1+S2<->ES1S2<->EP1P2<-> EP2+P1<-> E+P2 Must optimize one substrate then calculate kinetic parameters for the other Assumes k-2 = 0 Assume steady state conditions
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Sinh học - Chapter 5 (part 4): Enzyme regulationAcetyl-CoA Carboxylase acetyl-CoA + CO2 + ATP malonyl-CoA + ADP + Pi 1St committed step in fatty acid biosynthesis In presence of citrate activated In presence of fatty acyl-CoA inactivated
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Chapter 5 (part 3): Enzyme kinetics (cont.)Ping-Pong Reactions In Ping-Pong rxns first product released before second substrate binds When E binds A, E changes to F When F binds B, F changes back to E
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Sinh học - Chapter 5 (part 1) Enzymes: Introductionstudy of reaction rate determines number of steps involved determines mechanism of reaction identifies “rate-limiting” step
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Sinh học - Chapter 4 (part 3): 3 - D Structure/ FunctionSickle cell anemia – E6 to V6 Causes V6 to bind to hydrophobic pocket in deoxy-Hb Polymerizes to form long filaments Cause sickling of cells Sickle cell trait offers advantage against malaria Fragile sickle cells can not support parasite
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Sinh học - Chapter 4: Part 2 protein 3-D structure: 3o and 4o structure and protein foldingStabilize native structure Formed after native conformation achieved Abundant in secreted proteins but not in intracellular proteins Protein disulfide isomerase catalyzes reduction of incorrect disulfide linkages
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Sinh học - Chapter 4: Protein 3 - Dimensional structure and functionLoops Loops usually contain hydrophillic residues. Found on surfaces of proteins Connect alpha-helices and beta-sheets Turns Loops with < 5 AA’s are called turns Beta-turns are common
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Sinh học - Chapter 3 (part 2): Protein purification and AnalysisTrypsin Met-Ala-Arg Phe-Ala-Glu-Gln-Asp Gly-Glu-Tyr-Met-Cys-Lys Chymotrysin Met-Ala-Arg- Gly-Glu-Tyr Met-Cys-Lys –Phe Ala-Glu-Gln-Asp CNBr Met Ala-Arg-Gly-Glu-Tyr-Met Cys-Lys-Phe-Ala-Glu-Gln-Asp
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Sinh học - Chapter 3: Amino acids, peptides, and proteinsDraw the decapeptide at pH 1, 7, and 12. (pay attention to the form the N- and C- terminal and each R-group takes on at each pH) Calculate the overall charge at each pH. Write out the one letter code for the decapeptide
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