1. Enzymes!

2. Biological catalysts Proteins Specific Enzymes!
A substance that speeds up a chemical reaction without being used up in the reaction

3. Enzymes ... are catalysts
Every reaction involves breaking bonds, that requires energy. The rate of a particular reaction depends on the activation energy necessary to initiate it.
Catalysts reduce the activation of energy increasing reaction rates.

4. Enzymes ... are specific
Active sites are very specific pockets or clefts that only fit one kind of substrate
Folding of the peptide chain results in a globular protein with pockets/clefts

5. Enzymes ... are specific LOCK AND KEY MODEL
chemist Emil Fischer. Proposed the lock and key model.
KEY (substrate) has a specific shape (arrangement of functional groups and other atoms) that allows it and no other key to fit into the LOCK (the enzyme).

6. The substrate and enzyme complement each other
Therefore, they can fit together, like a lock and key.
Different molecules do not complement the enzyme's active site.

7. Enzymes ... are specific INDUCED FIT MODEL
Daniel E. Koshland Jr. modified the lock-and-key model
He proposed that binding of the substrate to the enzyme alters the configuration of both, providing a better fit.

8. Before binding, the substrate and enzyme do not exactly fit each other
Binding of the substrate to the enzyme changes the configuration of both so that they fit together.
Different molecules cannot induce a fit with the enzyme

10. Enzymes ... are affected by
CONCENTRATION
Increase substrate or enzyme concentration…Molecules more likely to collide…More reactions…Rates of reaction increases…Up to a point where the rxn reaches a maximum – saturation point.

11. Enzymes ... are affected by
TEMPERATURE
Increasing temperature –
Increases molecular movement …
more likely for enzyme and substrate molecules to meet…
Increases reaction rate.
Low temp: H-bonds and interactions that give the enzyme its shape aren’t flexible enough to permit the induced fit for optimum reaction rates
High temp: H-bonds and interactions are too weak to maintain enzymes shape due to increased movement of atoms making up the enzyme
              

13. Enzymes ... are affected bypH
Enzymes function at an optimum pH
Changing pH results in a change of balance of the hydrogen ion concentration and therefore the balance between positively and negatively charged amino acids making up the enzyme
Changes in the charges of the aa’s results in a change in the shape of the enzyme
Different enzymes have different optimal pH’s

15. Enzymes ... can be denatured
Denaturation = a structural change in a protein that results in a loss (usually permanent) of its biological properties.
When exposed to high temperature or extremes of pH

16. Type of reaction catalyzed
Classification of Enzymes
Enzyme Group
Type of reaction catalyzed
Examples
Oxidoreductases
Transfer of O & H atoms between substances, ie. all oxidation-reduction reactions
Dehydrogenases
Oxidases
Transferases
Transfer of a chemical group from 1 substance to another
Transaminases
Phophorylases
Hydrolases
Hydrolysis reactions
Peptidases
Lipases
Phosphatases
Lyases
Addition or removal of a chemical group other than by hydrolysis
Decarboxylases
Isomerases
The rearrangement of grops within a molecule
Mutases
Ligases
Formation of bonds between 2 molecules using energy derived from the breakdown of ATP
Synthestases

17. Naming of Enzymes
Start with the name of the substrate upon which the enzyme acts, ie. succinate
Add the name of the type of the reaction which it catalyzes, ie. dehydrogenation
Convert the end of the last word to an –ase suffix, ie. dhydrogenase
Thus: succinic dehydrogenase