Enzymes and Energy

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Enzymes and Energy
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Energy

• Definition
• Sun is the ultimate source of all earths energy
• Types of Energy
• Kinetic
• Potential
• Gravitational
• Chemical

• 1st Law of Thermodynamics
• Law of Conservation of Energy
• 2nd Law of Thermodynamics
• Entropy
• Energy must be added to maintain order or
  homeostasis

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Energy

• Adenosine Triphosphate
• ATP
• Structure
• Uses
• Instantly Accessible Energy
• Energy Currency of the Cell

• Store only enough to sustain the body for 20
  seconds.
• Hydrolysis of ATP
• ATP Water---gtADP P Energy
• occurs spontaneously
• exergonic or exothermic
• Endergonic

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Energy

• Exergonic Reactions
• Endergonic Reactions
• Coupling
• Phosphorylation
• ATP provides the energy to drive virtually all
  the bodys endergonic reactions.

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Enzymes

• Catalysts
• increase the rate of chemical reactions
• decrease the activation energy of a reaction.
• Structure
• Proteins
• Shape is very important
• Shape is maintained

• By hydrogen bonds and disulfide bonds
• Substrate
• Active Site
• Lock and Key Fit
• Shape is important along with the amino acids and
  charges found at the active site.

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Enzymes

• Enzymes may lower the activation energy by
• Substrate Orientation--Orient substrates so that
  they collide with the proper orientation to
  react.
• Physical Stress--when bonded to the active site,
  the bonds within a molecule may be stressed to
  the breaking point.

• Changes in Substrate Reactivity--the amino acids
  located at the active site may change the charge,
  electron distribution, and cause a general change
  in reactivity of the substrate.

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Enzymes

• Substrate
• Active Site
• Lock and Key Fit
• Conformational Changes
• Improves the fit between the enzyme and the
  active site.
• E S--gtES--gtE P

• Complementarity leads to a high degree of
  specificity.
• Each enzyme only catalyzes one reaction.
• Most enzymes are found in only certain locations
• Why is this important?

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Enzymes

• Cofactors
• Typically minerals
• Coenzymes
• Organic Compounds, Usually vitamins.
• Role
• Temperature Effect on Enzyme Activity
• Denaturation

• Optimum Temperature
• pH effect on Enzyme Activity
• Effect on Active site charge and shape
• Optimum pH

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Inhibitors

• Why doesnt this affect us?
• Noncompetitive inhibitors
• Penicillin
• Heavy Metals and arsenic as inhibitors
• Dont attach to active site.
• May change protein shape or bind in spots for
  cofactors.

• Bind to active site
• Block normal substrate binding, thus preventing
  the reaction to occur.
• Competitive inhibitors
• Sulfa Drugs
• block conversion of PABA to folic acid in bacteria

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Metabolic Pathways

• Definition
• Steps of reactions
• Metabolic Intermediates
• Different enzymes used to catalyze each reaction
  in the pathway.
• Many of the pathways are the same in all
  organisms.

• Catabolic pathways
• Anabolic pathways

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Oxidation and Reduction

• Oxidation
• Reduction
• relation to electrons
• relation to energy
• Fuels
• Why do they have so much energy?
• NADP
• NADPH

• Reducing power
• Covalent Modification of Enzymes
• phosphorylation
• protein kinases
• Speeds up catalytic activity of the enzymes.

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Feedback Inhibition

• Temporary deactivation of an enzyme brought about
  by an elevation of an end product of the pathway.
• Analogy to a thermostat.
• Feedback site
• Allosteric site

• Allosteric inhibitor
• Effect on active site
• Why does feedback inhibition exist?
• How is this process evolutionarily important?

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