Chemistry 2100 - PowerPoint PPT Presentation

chemistry 2100 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chemistry 2100 PowerPoint Presentation
Download Presentation
Chemistry 2100

play fullscreen
1 / 103
Download Presentation
Chemistry 2100
138 Views
Download Presentation

Chemistry 2100

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Chemistry 2100 Lecture 11

  2. Protein Functions Binding + L PL P Catalysis Structure

  3. Why Enzymes? • Higher reaction rates • Greater reaction specificity • Milder reaction conditions • Capacity for regulation • Metabolites have many potential pathways of decomposition • Enzymes make the desired one most favorable

  4. Specificity: Lock-and-Key Model • Proteins typically have high specificity: only certain substrates bind • High specificity can be explained by the complementary of the binding site and the ligand. • Complementarity in • size, • shape, • charge, • or hydrophobic / hydrophilic character • “Lock and Key” model by Emil Fisher (1894) assumes that complementary surfaces are preformed. +

  5. Specificity: Induced Fit • Conformational changes may occur upon ligand binding (Daniel Koshland in 1958). • This adaptation is called the inducedfit. • Induced fit allows for tighter binding of the ligand • Induced fit can increase the affinity of the protein for a second ligand • Both the ligand and the protein can change their conformations +

  6. Apoenzyme + Coenzyme = Holoenzyme

  7. Apoenzyme + Coenzyme = Holoenzyme

  8. Apoenzyme + Coenzyme = Holoenzyme

  9. Apoenzyme + Coenzyme = Holoenzyme

  10. Enzymatic Activity • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  11. TS • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  12. TS Ea • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  13. TS Ea • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  14. TS Ea • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  15. TS Ea • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  16. Ea ' TS Ea • increase [reactant] • increase temperature • add catalyst Potential Energy Reactants Products Reaction

  17. How to Lower G? Enzymes organizes reactive groups into proximity

  18. How to Lower G? Enzymes bind transition states best

  19. H2O + CO2HOCO2– + H+ Potential Energy Reaction

  20. H2O + CO2HOCO2– + H+ Potential Energy Reaction

  21. H2O + CO2HOCO2– + H+ Potential Energy Reaction

  22. H2O + CO2HOCO2– + H+ Potential Energy Reaction

  23. H2O + CO2HOCO2– + H+ Potential Energy Reaction

  24. H2O + CO2HOCO2– + H+ Ea Potential Energy Reaction

  25. Ea ' H2O + CO2HOCO2– + H+ Ea Potential Energy Reaction

  26. How to Do Kinetic Measurements

  27. Enzyme Activity Figure 23.3 The effect of enzyme concentration on the rate of an enzyme-catalyzed reaction. Substrate concentration, temperature, and pH are constant.

  28. Enzyme Activity Figure 23.4 The effect of substrate concentration on the rate of an enzyme-catalyzed reaction. Enzyme concentration, temperature, and pH are constant.

  29. Enzyme Activity Figure 23.5 The effect of temperature on the rate of an enzyme-catalyzed reaction. Substrate and enzyme concentrations and pH are constant.

  30. Enzyme Activity Figure 23.6 The effect of pH on the rate of an enzyme-catalyzed reaction. Substrate and enzyme concentrations and temperature are constant.

  31. What equation models this behavior? Michaelis-Menten Equation