The overview of metabolism

1. The overview of metabolism Associate professor Shi-Jie Liu,Ph D. Department of clinical pharmacology, Xinqiao hospital, TMMU.

3. An open system:Exchange mass and energy ΔS surrounding+ΔS system>0, biology capture negative entropy from surrounding

4. Metabolism: The total of all chemical reactions in an organism Purposes: To acquire free energy To acquire reduction potential To synthesize the structure unit molecules

5. The design of metabolism • The amount of reactions in metabolism is large, but the kind is small and the mechanisms are similar • A lot of molecules are involved in metabolism, but only a few of molecules play key roles in metabolism • The different metabolic pathways are controlled by similar mechanism

6. The design of biochemical reactions • Impossibilities of thermodynamics: Almost biochemical reactions do not spontaneously process without extra free energy • Impossibilities of kinetics: Almost biochemical reactions do not actually occur without catalysis of enzymes • Enzymes: Control almost biochemical reactions.

7. The role of enzymes in metabolism • Enzymes can’t change the direct of reactions, but decrease active enery of reactions • Pacemaker enzyme(or regulate enzyme): An enyme that catalyzes a committed step in a biochemical pathway

8. Anabolism: Large complex molecules are synthesized from smaller molecules. • Catabolism: Large complex molecules are degraded into smaller and simpler products • These two pathways are completely difference

9. The intermediate molecules • ATP: the energy currency • NADH/NADPH: the carrier of electrons • Coenzyme A: the carrier of acyl • Biotin: the carrier of CO2 • Isopentenyl pyrophosphate: the carrier of five-carbon structural units.

10. ATP+H2O=ADP+Pi ΔGº’=-7.3 kJ/mol ATP+H2O=AMP+PPi ΔGº’=-32.2 kJ/mol PPi+ H2O=2Pi ΔGº’=-32.2 kJ/mol Phosphate group transfer potential: the tendency of a phosphorylated molecule to undergo hydrolysis In cell: 500=[ATP]/[ADP][Pi]

13. The compartmentation of metabolism in eukaryote cell • Glycolysis: all in cytoplasm • Gluconeogenesis: Pyruvate carboxylase in mitochondria • Citric acid cycle: all in mitochondria • Fatty acid breakdown: all in mitochondrial matrix • Fatty acid synthesis: all in cytoplasm

14. Stage 1: The major nutrient molecules are degraded to building block molecules • Stage 2:The building block molecules are converted to a small number of simpler molecule,such as acetyl-CoA • Stage3: The acetyl group of acetyl-CoA enters the citric acid cycle and is completely oxidized.

15. The regulation of metabolism • The amount of enzyme in metabolism is controlled • The activity of enzyme is controlled by: • Allosteric regulation • Covalent modification • Compartmentation • The anabolic and catabolic pathways are completely difference • Many reactions are controlled by state of energy.

16. Summary • The system of living organism • Metabolism, anabolic and catabolic pathway • The purposes of metabolism • The design of reactions in thermodynamics and kinetics • Three stages of energy captured from food • The regulation of metabolism

17. Key words • System of living organism • Metabolism; Anabolism; Catabolism • Genetic control, Allosteric regulation, Covalent modification, Compartmentation • ATP; NADH/NADPH; Biotin; Coenzyme CoA; Actyl-CoA; Isopentenyl pyrophosphate

18. Thanks