Adsorption, Binding and Catalysis Chapter 27

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Adsorption, Binding and CatalysisChapter 27

• Sune Nørhøj Jespersen

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Learning objectives

• After working with this material, you should be
  able to
• Derive the Langmuir model for surface binding.
• Use the Langmuir model to describe other
  saturable processes
• Binding in solution.
• Gas chromatography.
• Michaelis-Menten kinetics.
• Transport across biological membranes.
• Surface catalysis.

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Surface adsorption

• Equilibrium

Since
We need
Surface Binding energy
(Particles gain energetic advantage from sticking)
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Adsorption
Entropy
Surface sites
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Adsorption
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Adsorption

• Gas phase
• Where
• Surface

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Adsorption

• In equilibrium

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Adsorption

• Define a binding constant
• or

Langmuir equation
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Adsorption
Intermediate
Large
Small
p
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Binding in solution
so
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Michaelis-Menten
The reaction is catalysed by enzyme
E. We assume that is small enough to render
the first reaction approximately in
equilibrium. And reverse reaction very slow.
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Michaelis-Menten
Total enzyme contration
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Michaelis-Menten
or in terms of the dissociation constant
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Transport across membranes
Ligand Concentration
Ligand Concentration
E
E
ES
ES
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Transport across membranes

• Repeating the logic in Michaelis-Menten
  derivation we find the solute flux
• of solute from left to right, and

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Passive transport
If transport to
the right side
If transport to
the left side
i.e. Transport to equilibrate concentration on
both sides. When and
i.e. Ficks law
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Active transport

• if we can still have flux to the left
  when