1. BIBC 102
Metabolic Biochemistry
Randy Hampton

2. Metabolic Biochemistry BIBC 102
BIBC 102 Web Site
IA/TA sections start
Monday Oct 8
IA/TA office hours (1 per wk)
Posted soon
My office hours
2130 Pacific Hall
Tue 5-6

3. Ask… or
txt:

4. Energy map of a reaction
fig6-2
DG‡ is the activation energy

5. altering rate by catalysis
enzymes alter DG‡. period
fig6-3

6. how enzymes alter reactions: no enzyme
fig6-5

7. how enzymes alter reactions: plus enzyme
fig6-5

8. covalent intermediates
Main Enzymatic Catalytic Mechanisms
entropy reduction
acid-base catalysis
metal ion catalysis
covalent intermediates
other, stranger things… rh

9. Main Enzymatic Catalytic Mechanisms
entropy reduction rh

10. entropy reduction: reaction 1
fig6-7

11. entropy reduction: reaction 2
about 105 times faster
fig6-7

12. entropy reduction: reaction 3
about 108 times faster
fig6-7

13. entropy reduction: Off the CHAIN!

14. entropy reduction acid-base catalysis
Main Enzymatic Catalytic Mechanisms
entropy reduction
acid-base catalysis rh

15. recall from O-chem... acids and bases enhance
rates of reactions like this

16. fig6-9

17. entropy reduction acid-base catalysis metal ion catalysis
Main Enzymatic Catalytic Mechanisms
entropy reduction
acid-base catalysis
metal ion catalysis rh

18. ions as cofactors
table 6-1

19. covalent intermediates
Main Enzymatic Catalytic Mechanisms
entropy reduction
acid-base catalysis
metal ion catalysis
covalent intermediates rh

21. covalent intermediates
Main Enzymatic Catalytic Mechanisms
entropy reduction
acid-base catalysis
metal ion catalysis
covalent intermediates
other, stranger things… rh

22. “UN-REQUIRED” READING
not required, but interesting

23. Activation energy and reaction rate
fig 6-2

24. Activation energy and reaction rate
fig 6-3

25. What is the relation between changes in activation energy
and reaction rate?

26. S P k dS/dt = k[S] Activation energy and reaction rate blue terms are
constant when
temperature is
constant...

27. Activation energy and reaction rate
designate blue terms as constants

28. Activation energy and reaction rate
call DG‡ = A for simplicity

29. Lowering activation energy …

30. Lowering activation energy …
when DG‡ is lowered by this amount: d
the rate constant is increased by this factor:
note the following features:
lowering DG‡ makes reaction faster
identical effect on both directions

31. how big a deal is this?
recall that C2 = RT
at body temp, RT= 2573 J/mole
so if DG‡ changes by the value of one
hydrogen bond (~20 kJ/mole)
rate enhancement is e7.8 = 2440

32. Ask… or
txt:

33. If you have not already
please read
LIGAND BINDING
and
ENZYME CATALYSIS

34. If you have not already
please read
LIGAND BINDING
and
ENZYME CATALYSIS

35. Ligand Binding rh

36. Does this form make intuitive sense?
when there is no L, LB is also 0
as L gets big, LB approaches B
saturable rh

37. Binding isotherm
rectangular hyperbola rh

38. Enzyme kinetics: binding and beyond
when there is no S, reaction rate is 0
as S gets big, rate reaches a maximum
saturable rh

39. Vmax S Km + S Vo = Michaelis-Menten Equation
Maud
Menten
again, a rectangular hyperbola rh

40. Vmax S Km + S Vo = Michaelis-Menten Equation
when there is no S, V0 is also 0
as S gets big, V0 approaches Vmax
saturable rh

41. fig 6-11

42. how fast can an enzyme “do” a reaction?
Vmax = kcat[E]T
table 6-7

43. Competition for binding
remember to tell
them about I and Y
feature of saturability rh

44. action of a competitive enzyme inhibitor
fig 6-15

45. action of a uncompetitive inhibitor
fig 6-15

46. a “suicide” inhibitor
catalytic action of enzyme causes
permanent covalent inhibition
fig 6-16

47. CHYMOTRYPSIN: a protease

48. CHYMOTRYPSIN: a protease
fig 6-18

49. catalytic
triad
fig 6-21

50. fig 6-21

51. fig 6-21

52. fig 6-21

53. fig 6-21

54. fig 6-21

55. fig 6-21

56. fig 6-21

57. fig 6-21