The document presents information on enzyme models. It discusses how enzyme models are synthetic molecules that contain features of enzymatic systems and mimic biological reactions. Examples of molecules used to create models include crown ethers, micelles, ionophores, and cyclodextrins. Cyclodextrins are particularly effective models as their cavity can facilitate reactions like selective substitution and ester hydrolysis in a similar way to enzymes. The document concludes that effective enzyme models exhibit hydrophobic interactions for substrate binding, provide a medium effect through proper polarity, and induce orientation effects through conformational restriction.

1. ENZYME
MODELS
PRESENTED BY:
Jatinder Kumar
2016CYB1265
Reference: Hermann Dugas & Christopher Penney,
Bioorganic chemistry(A chemical approach to
enzyme action), Chapter 5

2. CONTENTS:
Introduction
Enzyme Modeling
Examples Of Enzyme Models
Cyclodextrins As Enzyme Models
Conclusion

3. Introduction
Enzyme models are synthetic organic
molecules that contain one or more features
present in enzymatic systems.
They are structurally smaller and simpler than
enzymes itself.
It is often referred to as biomimetic chemical
approach .
The word was first introduced by R. Breslow
in 1972 and generally refers to any aspect in
which a chemical process imitates a biological
reaction.

4. Enzyme Modeling
For making particular enzyme mimics certain
points should be kept in mind:
Structure of the active site and the enzyme
substrate complex;
Specificity of the enzyme and its ability to
bind to the substrate;
Kinetics for the various steps and a
knowledge of possible intermediates in the
reaction coordinate.

5. Examples:
Some of the molecules which can be employed
to make enzyme models are:
Crown ethers
Micelles
Ionophores
Cyclodextrins
Various polymers etc.
They shows host-guest
complexation
chemistry

6. Cyclodextrins:
Inner diameter
of cyclodextrin
is 0.45nmApplication of
cyclodextrin to
biomimetic
chemistry was
originated by
F.Cramer in 1965

7. Selective para substitution reaction on anisole
in presence of cyclodextrin:
The schematic representation above
shows an anisole molecule in the cavity
of cyclohexaamylose. One or more
hydroxyl groups can be converted to a
hypochlorite to explain the increased
rate of chlorination in the complex.
It illustrates
non-covalent
catalysis

8. Ester hydrolysis with cyclodextrin:
This is an
example of
covalent
catalysis

9. This model was developed by Breslow & Overman

10. First successful
carbonic
anhydrase model
developed by
Tabushi’s team.
In the presence of Zn(2+)
regiospecific hydrolysis of
𝐂𝐎 𝟐 can be done.
Zn(2+)
binding with
imidazole
rings
enhances the
activity.

11. Conclusion:
For the enzyme models, the catalytic efficiency
appears to be understandable in terms of
three main effects:
Hydrophobic interactions to provide an
efficient binding;
A medium (or cavity) effect where proper
polarity provides a large driving force for the
reaction;
An orientation effect that leads to restriction
of conformation and provides a large rate
acceleration.