1. Friday, March 5 th

2. Quick Review Entropy vs enthalpy Gibbs free energy (ΔG) What reactions are likely to occur?

3. A bit more chem… Attaching P i = “phosphorylation” More reactive Ex. Active transport (phosphorylated protein carriers) Abstracting P i = “dephosphorylation” How important is this….really? Very.

4. De/phosphorylation

5. Redox Reactions Loss of electrons = oxidation Gain of electrons = reduction An electron transfer always involves an oxidation, reduction  “redox”

6. Redox Reactions Leo the Lion says “Ger!”Oil rig

7. Classic redox example

8. Coupled redox reactions The product of one redox rxn = reactant in the next rxn in series

9. Enzymes (“-ase”) Def? Protein catalyst Reduces E A barrier Substrate Site-specific (conformation-specific) Active site Location, location, location

10. Enzymes (“-ase”) E-S complex

12. Enzyme function Factors that affect rate Enzyme saturation Cofactors and coenzymes (Zn, Mn; vitamin B3) Molecule shuttles

13. Enzyme Inhibition Competitive vs non-competitive

14. Allosteric Regulation Activators vs inhibitors

15. Another form of regulation Feedback inhibition In a series of reactions +++ product inhibits enzyme responsible for initial reaction Reduces production of the inhibiting agent Effect is tight control