BCH 311 Exam 2 Study guide

BCH 311 Exam 2 - Lipitor(atorvastatin calcium synthetic cholesterol-reducing agentinhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A(HMG-CoA

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Lipitor (atorvastatin calcium)- synthetic cholesterol-reducing agent…inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase Gleevec-Imatinib mesylate-discovered to bind to catalytic cleft of the BCR-ABL tyrosine kinase---option for leukemia Catalysis-extremely important, w/o it reactions=slow Vast majority of enzymes globular proteins Enzymes-increase rate of reaction as high as 10^20 times Non-enzymatic catalysts, increase rate 10^2 to 10^4 quicker Enzymes-highly specific-able to distinguish between stereoisomers ΔG (free energy change) – Δenergy reactants and products -Determines whether a reaction is favorable or not, enzymes do not alter ΔG. . ΔG *T =free energy of activation/activation energy- which is energy required to initiate the reaction, Ae higher when no catalyst is involved, uncatalyzed take more energy to get started Respiration –favorable(spontaneous) because ΔG is negative (- 2880 KJ/mol) Ae effects rate of reaction, enzymes speed up by lowering Ae Energy releasing ΔG<0, while the opposite is energy absorbing Free energy of activation is to the top of the “hill” Ae = energy to bring reactants to transition state, Ae is changed when a catalyst is added, free energy does not change Hydrogen peroxide to water and oxygen—enezyme=catalase Rate of reaction inceases as T increases, closer to transition state Six classes of enzymes: 1. Oxidorductases- transfer of e-‘s(hydrid ion or H atoms) Structure of Oxidorductases: A- + B A + B- 2. Transferases- group transfer reactions Structure: A –B + C A + B—C 3. Hydrolases – Hydrolysis reactions (transfer functional to H2O) Structure: A –B + H2O A – H + B –OH 4. Lyases – Add groups to double bonds/form doubles by removal Structure: X down to A—B up to Y A=B + X –Y 5. Isomerases: Transfer group to yield isomeric form—in molecule Structure: X down to A –B up to Y Y down to A-B up to X 6. Ligases – Form C-C, C-S, C-O, C-N condense-(ATP cleavage) Aka (synthases)….Structure: A + B A – B E bind to sub (S) for ES and EP complex with the following: E + S ES EP E + P…transition state species that forms E and S bind in a cleft=active site-where AA’s are for eynzmatic Reactions----specific interactions AA and subs in active site Lock-Key Model-similar shape assume Enzyme site and S Induced-fit=conformational change, then fits-3d flexibility If E with S ES was perfect, ES would be at a tiny energy Catalysis occurs after sub bound and transition state formed Induced fit=more accurate-explains E + S transition state In order to catalyze, enzyme=complementary to trans. State ==Optimal interactions between sub and E occur in tran. State This is where Ae is lowered, and the reaction rate increases Full complement of such interactions between S and E is formed only when the substrate reaches the transition state Unfavorable—ΔG is positive….Favorable--- ΔG is negative When the reaction = favorable, Ae is lowered, quicker reaction
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This note was uploaded on 03/21/2011 for the course BCH 311 taught by Professor Howlett during the Spring '08 term at Rhode Island.

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BCH 311 Exam 2 - Lipitor(atorvastatin calcium synthetic cholesterol-reducing agentinhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A(HMG-CoA

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