Post on 05-Jan-2016
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Bacterial MetabolismBacterial Metabolism
IntroductionEnzymes
Energy ProductionBacterial Catabolism
Bacterial Metabolism 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
Bacterial MetabolismBacterial Metabolism
Enzyme Introduction Enzyme Components Enzyme Mechanism Factors Influencing Enzymes
Bacterial MetabolismBacterial 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
Bacterial MetabolismBacterial Metabolism
Enzymes work to lower activation energy
Bacterial MetabolismBacterial 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
Bacterial MetabolismBacterial Metabolism
How enzymes speed up reactions– Proximity– Orientation– Induced fit– Reactive groups– Cofactors
Bacterial MetabolismBacterial 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
Bacterial MetabolismBacterial Metabolism
Bacterial MetabolismBacterial Metabolism
Factors Influencing Enzymes– Temperature– pH– Salt concentration– Inhibitors
»Competitive (active site)»Non - Competitive (allosteric)
– Feedback Inhibition
Bacterial MetabolismBacterial Metabolism
Energy Production– Oxidation / Reduction reactions– Role of ATP– Phosphorylation
»Substrate»Oxidative»Photo-
Bacterial MetabolismBacterial Metabolism
Oxidation / Reduction– Oxidation - loss of electrons– Reduction - gain of electrons– Redox reactions always coupled– Oxidation of reduced carbon tends to
be energetically favorable
Bacterial MetabolismBacterial Metabolism
Carbon Oxidation/Reduction– Carbon Dioxide CO2 (+4)
– Acid (Formic Acid HCO2) (+2)
– Aldehyde (Formaldehyde - H2CO) ( 0 )
– Alcohol (Methanol - H3COH) (-2)
– Methane CH4 (-4)
Bacterial MetabolismBacterial Metabolism
Oxidation States– Alcohols– Fats– Organic Acids (acetic acid)– Glucose
Bacterial MetabolismBacterial Metabolism
Role of ATP– ATP ADP + Pi
– Energy intermediate or “currency”– Hydrolysis of ATP “coupled” to
energetically unfavorable reactions
Bacterial MetabolismBacterial Metabolism
Bacterial MetabolismBacterial Metabolism
Glucose + Pi Glucose-6-PO4 + H2O
ΔG = +13.8 kJ/mol, Keq = 5 x 10-3 ATP + H20 ADP + Pi
ΔG = -30.5 kJ/mol, Keq = 4 x 105 Glucose + ATP Glucose-6-PO4 +
ADP ΔG = (-30.5 kJ/mol) + (+13.8 kJ/mol)
= -16.7 kJ/mol
Bacterial MetabolismBacterial 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
Bacterial MetabolismBacterial 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