Bacterial Metabolism

1
Bacterial Metabolism

• Introduction
• Enzymes
• Energy Production
• Bacterial Catabolism

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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

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Bacterial Metabolism

• Enzyme Introduction
• Enzyme Components
• Enzyme Mechanism
• Factors Influencing Enzymes

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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

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Bacterial Metabolism

• Enzymes work to lower activation energy

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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

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Bacterial Metabolism

• How enzymes speed up reactions
• Proximity
• Orientation
• Induced fit
• Reactive groups
• Cofactors

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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

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Bacterial Metabolism
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Bacterial Metabolism

• Factors Influencing Enzymes
• Temperature
• pH
• Salt concentration
• Inhibitors
• Competitive (active site)
• Non - Competitive (allosteric)
• Feedback Inhibition

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Bacterial Metabolism

• Energy Production
• Oxidation / Reduction reactions
• Role of ATP
• Phosphorylation
• Substrate
• Oxidative
• Photo-

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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

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Bacterial Metabolism

• Carbon Oxidation/Reduction
• Carbon Dioxide CO2 (4)
• Acid (Formic Acid HCO2) (2)
• Aldehyde (Formaldehyde - H2CO) ( 0 )
• Alcohol (Methanol - H3COH) (-2)
• Methane CH4 (-4)

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Bacterial Metabolism

• Oxidation States
• Alcohols
• Fats
• Organic Acids (acetic acid)
• Glucose

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Bacterial Metabolism

• Role of ATP
• ATP ? ADP Pi
• Energy intermediate or currency
• Hydrolysis of ATP coupled to energetically
  unfavorable reactions

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Bacterial Metabolism
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Bacterial Metabolism

• Glucose Pi ? Glucose-6-PO4 H2O
• ?G 13.8 kJ/mol, Keq 5 x 10-3
• ATP H20 ? ADP Pi
• ?G -30.5 kJ/mol, Keq 4 x 105
• Glucose ATP ? Glucose-6-PO4 ADP
• ?G (-30.5 kJ/mol) (13.8 kJ/mol)
• -16.7 kJ/mol

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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

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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
• Krebs or Tricarboxylic Acid (TCA) cycle
• Electron transport /oxidative phosphorylation