Types of Enzymes

Hasnain A.

Enzyme as a function is a catalyst. It carries chemical reactions of living organisms. At normal

temperature, pH and cellular pressure, the reaction rate is high. On the basis of structure there are 1300

types of enzymes in the cell of human body. Functionally enzymes are divided into seven major groups;

oxidoreductases, transferases, hydrolases, isomerases, lyases, ligases and translocases.

1.Oxidoreductases: These type of enzymes catalyze oxidation reduction reaction. Electrons tend to

travel from one particular molecule to the other. It depends upon substrate whether the reaction is

oxidation or reduction. Pyruvate dehydrogenase is used to catalyze the oxidation of pyruvate which is

2.Transferases: Enzymes in this class help to transport the functional group among acceptors and donor

molecules. Transaminase transfers an amino group from a molecule to another.

3.Hydrolases: These are hydrolytic enzymes; catalyze hydrolysis reaction by adding water, cleave the

bond and hydrolyze it. Pepsin have the ability to break peptide bonds in protein.

4.Isomerases: Enzymes in this group catalyze structure; causing the change in shape of the molecule.

The new molecule is called isomer of parent molecule. Phosphoglucomutase converts glucose-1-

5.Lyases: This is very strange group; they add water, CO2 or NH3 across double bond and sometimes

eliminate these products to create double bonds. These enzymes break the bond without catalysis e.g.

aldolase catalyzes fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone

6.Ligases: The ligases are known to charge the catalysis of ligation process. In this process two molecules

associate to form a complex molecule e.g. DNA ligase catalyzes two fragments of DNA, then

7.Translocases: This is a new class of enzymes. It assists the molecules to move across the cell

membrane. Sometimes the movement is done to separate the ion or molecule within membrane e.g.