2. Lecture 3 August 5, 2005 Lehninger (4 th Edition), Chapter 13

3. METABOLIC PATHWAYS

4. Types of Organic Reactions 1) Group transfer Glucose + ATP Glu-6-P + ADP H 2 O + ATP P i + ADP 2) Oxidation-reduction reactions Ethanol + NAD + acetaldehyde + NADH + H + 3) Eliminations, isomerizations, rearrangements aldose ketose 4) reactions involving making or breaking of C-C bonds Fru-1,6, bisphosphate dihydroxyacetone-phosphate + glyceraldehyde-3phosphate

5. Biochemical reactions are subject to the laws of thermodynamics

6. A + B C + D  G = 0 at equilibrium

8. Gas constant R = 8.313 J/mol. K = 1.987 cal/mol. K 1 cal = 4.184 J at 25 o C RT = 2.497 kJ/mol = 0.592 kcal/mol

11. Many reactions in biological systems are by themselves not energetically favored (  G > 0) they have to be “pushed” 1. By changing concentrations of reactants 2. By coupling them to energy releasing reactions 3. enzymatic mechanisms are designed to accomplish this

12. HIGH ENERGY PHOSPHATE COMPOUNDS ATP

13. __ _ _ ___ _

14. _ _ _ _ _

15. a mixed anhydride

18. LNC 14-8

19. Oxidation - Reduction Reactions a second major source of chemical free energy for biological work

20. - 4 - 1

21. + 1 + 2 + 4

22. LNC 14.14

23. [lactate] [NAD+]  G =  G o ’ + RT ln --------------------------- [pyruvate] [NADH] [lactate] [NAD+]  E =  E o ’ - RT/n F ln --------------------------- [pyruvate] [NADH]  G = - n F  E

25. transfer of hydride ion (two electrons) in one step LNC 14-15a

26. LNC 14-15b

27. FAD FMN LNC 14-16 two steps one electron and one proton transferred in each step

28. METABOLIC PATHWAYS

29. End of lecture 3 August 5, 2005