1. Why study enzyme kinetics?  To quantitate enzyme characteristics  define substrate and inhibitor affinities  define maximum catalytic rates  Describe how reaction rates vary with reaction conditions  Provide an understanding of an enzyme’s role in a metabolic pathway  Define the conditions under which the rate of the reaction is proportional to the amount of enzyme present  biochemical and clinical enzyme assays

2. Enzyme Kinetics

3. First- and Second- order reactions First-orderSecond order

4. Half-life of first-order reactions When [A] = 1/2 the initial concentration [A] 0 (For a second-order reaction: t 1/2 = 1/k [A] o )

5. Decay curves for 1st and 2nd order reactions of same half-life

6. First- and Second- order reactions First-orderSecond order Ln[A] Time 1/[A] ln[A] = ln[A] 0 -kt 1/A = 1/A 0 + kt ln[A] 0 Slope = -k 1/A 0 Slope = k

8. Thermodynamics of the Transition State

11. Plots of Initial rates and Reactant Concentrations Differ for enzymatic and non-enzymatic reactions Non- enzymaticenzymatic

12. Michaelis-Menten Model Assumptions

13. Michaelis-Menten Model Derivations

14. Michaelis-Menten Model Derivations (cont’d)

15. Km and Vmax Derivation and significance

16. Lineweaver_Burk Double reciprocal plot

17. Graphical Representations of Changes in Km and Vmax

18. Graphical Representations of Changes in Km and Vmax (cont’d)

19. Use of “turnover number” and “catalytic efficiency” as measures of enzyme behavior

20. Kinetic constants for some enzymes and substrates

21. Reversibility of the reaction adds complexity to the rate equation For the simple reversible reaction The velocity of the reaction is: Where When [P] =0, i.e. when v = v 0 then the more familiar Michelis-Menten form is evident:

22. Enzyme Inhibition: Irreversible

23. Enzyme Inhibition: Reversible

24. Enzyme Inhibition: Reversible (mixed)

25. Enzyme Inhibition: Reversible (competitive)

27. Enzyme Inhibition: Reversible (competitive)

28. Enzyme Inhibition: Reversible (competitive)

29. Enzyme Inhibition: Reversible (uncompetitive)

31. Enzyme Inhibition: Reversible mixed (non-competitive)

36. Use of Substrate or Product Absorbance to Measure Rates of a Reaction