1. Multienzyme systems A soluble or dissociated multienzyme system
with diffusing intermediates A, B, C S A B C P E1 E2 E3 E4

2. Multienzyme systems Multienzyme complex
Intermediates in the reaction sequence catalyzed by an enzyme complex are covalently bound and do no diffuse away from the complex E7 E2 E6 E1 E3 E5 E4

3. Multienzyme systems Membrane bound enzyme systems
Large supramolar structures such as membranes or ribosomes
Terminal oxydation chain

4. e- H+ H+ H+ H+ H+ + + + + + Cit c III. I. e- UQ e- II. e- e- - - - -
IV. e- e- - - - -
NADH + H+
Szukcinát
4 H+ + O2
NAD+
Fumarát
H2O

5. Multienzyme systems Kinetical behaviour
Each component has an own Km for substrate, cofactor, Vmax and pH optimum
Computer modell
Regulatory enzyme
Fatty acid synthetase
Pyruvate-dehydrogenase
.a-ketoglutarate dehydrogenase
Branched chain amino acid dehydrogenase

6. Pyruvate-dehydrogenase (PDH)
Glucose
glycolysis
Pyruvate
Pyruvate-dehydrogenase
enzyme complex

7. Piruvát - dehidrogenáz
Kofaktorok:
NAD+
HS-CoA
Koenzimek
Tiamin-pirofoszfát (TPP)
Liponsav
Prosztetikus csoportok
FAD

8. A piruvát-dehidrogenáz multienzim komplex (PDH – komplex)
E1: Piruvát dehidrogenáz a2 b2 (20-30)
Protein-kináz
E2: Dihidrolipoil-transzacetiláz (60)
x: alegység (6)
Foszfoprotein-foszfatáz
E3: Dihidrolipoil-dehidrogenáz (6) X E1 b E2 E3 E1 a
TPP-
FAD

9. A PDH komplex szabályozása
aktív +
ATP
NADH + H+
Acetil-CoA -
Piruvát (máj) X +
Inzulin
(zsírszövet) E1 b E2 E3 E1 a
HPO42-
ATP
PDH-kináz
PDH-foszfatáz
inaktív
ADP X
H2O
Ca2+
ADP, NAD+
HS-CoA
koncentráció
növekedése
esetén E1 b E2 E3 E1 a