1. Introduction Enzymes Energy Production Bacterial Catabolism
Bacterial Metabolism
Introduction
Enzymes
Energy Production
Bacterial Catabolism

2. Bacterial Metabolism Introduction
Metabolism - sum of all chemical reactions in cell
Anabolism - reactions that synthesize or “build up” e.g. protein synthesis
Catabolism - reactions that digest or “break down” e.g. starch to glucose

3. Bacterial Metabolism Enzyme Introduction Enzyme Components
Enzyme Mechanism
Factors Influencing Enzymes

4. Bacterial Metabolism Enzyme Introduction
Enzymes are biological catalysts
Catalysts are agents which speed up a reaction
Enzymes are very specific
Enzymes are typically proteins
Catalysts work by lowering the activation energy of a reaction

5. Bacterial Metabolism
Enzymes work to lower activation energy

6. Bacterial Metabolism Enzyme Components
Cofactor - nonprotein component that is part of enzyme, e.g. Fe, NAD+, biotin
Apoenzyme - protein portion of enzyme
Holoenzyme - Cofactor plus apoenzyme

7. Bacterial Metabolism How enzymes speed up reactions Proximity
Orientation
Induced fit
Reactive groups
Cofactors

8. Bacterial Metabolism Enzyme Mechanism
Substrate binds to active site; lock & key specificity; induced fit
Formation of enzyme-substrate complex
Catalytic activity; localized acid or base or induced fit

9. Bacterial Metabolism

10. Bacterial Metabolism Factors Influencing Enzymes Temperature pH
Salt concentration
Inhibitors
Competitive (active site)
Non - Competitive (allosteric)
Feedback Inhibition

11. Bacterial Metabolism Energy Production Oxidation / Reduction reactions
Role of ATP
Phosphorylation
Substrate
Oxidative
Photo-

12. Bacterial Metabolism Oxidation / Reduction
Oxidation - loss of electrons
Reduction - gain of electrons
Redox reactions always coupled
Oxidation of reduced carbon tends to be energetically favorable

13. Bacterial Metabolism Carbon Oxidation/Reduction
Carbon Dioxide CO2 (+4)
Acid (Formic Acid HCO2) (+2)
Aldehyde (Formaldehyde - H2CO) ( 0 )
Alcohol (Methanol - H3COH) (-2)
Methane CH (-4)

14. Bacterial Metabolism Oxidation States Alcohols Fats
Organic Acids (acetic acid)
Glucose

15. Bacterial Metabolism Role of ATP ATP  ADP + Pi
Energy intermediate or “currency”
Hydrolysis of ATP “coupled” to energetically unfavorable reactions

16. Bacterial Metabolism

17. Bacterial Metabolism Glucose + Pi  Glucose-6-PO4 + H2O
ΔG = kJ/mol, Keq = 5 x 10-3
ATP + H20  ADP + Pi
ΔG = kJ/mol, Keq = 4 x 105
Glucose + ATP  Glucose-6-PO4 + ADP
ΔG = (-30.5 kJ/mol) + (+13.8 kJ/mol)
= kJ/mol

18. Bacterial Metabolism Phosphorylation
Substrate - direct transfer of phosphate from an organic molecule to ADP
Oxidative - ATP generated via chemiosmosis (“proton pump”) and ATP synthase
Photo - light energy from photosynthesis, a modification of chemiosmosis

19. Bacterial Metabolism Bacterial Catabolism
Carbohydrate catabolism has two functions:
energy production and/or storage
generation of chemical intermediates
Cellular respiration and fermentation
Includes three processes:
Glycolysis
Kreb’s or Tricarboxylic Acid (TCA) cycle
Electron transport /oxidative phosphorylation