1. Lecture 4 Web: pollev.com/ucibio Text: To: 37607 Type in: 169964

2. Enzymes and reactions Spontaneity = ___ Enzyme = Decrease G# = _________________ Mechanism = “Induced fit” Rate = ___ “Active site” ________________ stabilize TS

3. Decreasing  G ‡ : Proximity + Orientation Active site: Bring products together In precise orientation

4. Not just binding! Forces change in substrate conformation as well! Active site interactions can stabilize the TS Active site residues can initiate reactions Keep molecules under “strain” to facilitate reaction Different enzymes = Different mechanisms

5. Glc  Glc-6-P: Enzyme = Hexokinase http://web.chem.ucsb.edu/~molvisual/ABLE/induced_fit/index.html

6. Specificity of enzymes - Isomers

7. Specificity of enzymes - Stereoisomers

8. Effects of specificity – Tastes!

9. Effects of specificity – Calories! http://commons.wikimedia.org/wiki/File:D_et_l_glucose.png

10. Effects of specificity – Treatment!

11. 3D shape is important! OK. Fine. So the shape of the active site is important How is the shape formed?

12. Formation of active sites

13. Active site review Small part of total enzyme 3D architecture is important Specific residues important Not necessarily contiguous residues

14. How does an active site form? Protein must “fold”into structure How does protein “fold?” First, understand protein composition Proteins made up of _____________

15. What is an amino acid? Molecule with _____ group and ___________ group Each amino acid has a different “R” group There are _____ different amino acids H2NH2NCOOHC R H

16. Amino acids, pH and charge

17. Amino acid titration curve

18. Asp titration curve

19. Amino acids in cells… H2NH2NCOOHC R H

20. The Peptide bond: Joining amino acids

21. Nomenclature: N t -> C t

22. Charge on peptides is cumulative

23. OK. What does this all have to do with enzymes? What is needed for proteins to fold correctly? Can we design experiment to test?