1. ENZYMES

2. Enzymes Enzymes are protein catalysts
A catalyst is a substance that speeds up a chemical reaction without being used up in the process
Rates of chemical reactions could be increased with the addition of heat, however heat may denature proteins
A catalyst can speed up the rate of chemical reactions at moderate temperature decreasing risk of denaturation

3. Enzymes
The substrate is the reactant that an enzyme acts on when it catalyzes a chemical reaction
Enzymes are very specific for the substrate to which they bind
Name of enzymes ally end in –ase (ex. lactase, polymerase, maltase, etc.)

4. How Do Enzymes Work?
In an enzyme-catalyzed reaction, the substrate binds to a very small portion of the enzyme
The location where the substrate binds is called the active site
The substrate must fit into a pocket or groove of the 3D structure of the protein
Once the substrate binds to the enzyme, the structure is called the enzyme/substrate complex

6. Induced-Fit Model
As the substrate enters the active site, its functional groups come close to the functional groups of a number of amino acids in the enzyme
This causes the enzyme to change shape slightly to accommodate the substrate
This slight change in shape causes the substrate to become “stressed” (distorting a particular bond) and, therefore, lowers the activation energy needed to break the bonds

8. When the bonds are broken the conformation of the substrate changes and the enzyme loses its affinity for the products releasing them back into the environment
The active site now becomes available for another substrate to attach
The recycling of enzyme molecules causes cells to catalyze many reactions with relatively small numbers of enzymes

10. Co-factors & Co-enzymes
Some enzymes require additional assistance to function
These co-factors and co-enzymes are not proteins
Co-factors:
Inorganic metal ions such as Zn2+ and Mn2+
They help draw out electrons from the substrate where bonds need to be broken

12. Co-enzymes Organic Shuttle molecules from one enzyme to another
Examples: NAD+ and FAD+
These usually get reduced to harvest energy
Act as electron carriers