This document discusses the classification and properties of enzymes. It describes the six main classes of enzymes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Oxidoreductases catalyze oxidation-reduction reactions, transferases transfer chemical groups between molecules, hydrolases catalyze hydrolytic cleavage of bonds, lyases catalyze non-hydrolytic bond cleavages or additions, isomerases convert molecules between isomers, and ligases catalyze bond synthesis coupled with ATP breakdown. Examples of each enzyme class are provided.

1. DPT 3RD SEMESTER
Biochemistry
CLASSIFICATION AND
PROPERTIES OF ENZYME

2. Classification
6 classes:
 Oxidoreductases
 Transferases
 Hydrolases
 Lyases
 Isomerases
 Ligases

3. Oxidoreductases
 This class belongs to catalyze
oxidation-reduction reaction
 Reduction= addition of H+
 Oxidation = removal of H+
 AH2 + B A + BH2
 Example: oxidases, dehydrogenases ,
reductases

5. Transferases
 Transfer chemical group of one molecule to
another or to another part of the same molecule
 Catalyze group transfer reactions, excluding
oxidoreductases
 A-X + B BX + A
 EXAMPLE: transaminases ( transfer amino group
)
 Kinase(transfer phosphate group)

6. Hydrolases
 Catalyze hydrolytic reaction
 These enzymes catalyse the
hydrolytic cleavage of C-O,C-N ,C-C
and some other bonds .
 A-X + H2O X- OH +A-H
Example: lipase
Amylase

7. Lyases
 Catalyze non- hydrolytic . Catalyzes the
breaking of various chemical bond i.e C-C, C-N
or also catalyze the addition to C=C , C=O
,C=N
 A-X + B- Y A= B + X- Y
 Example : decarboxylases , dehydrases

8. Isomerases
 Convert a molecule from one isomer
to another .Catalyzes isomerization
reaction”
 A A’
 EX: isomerases
 Epimerases

9. Ligases
 Catalyzes the synthesis of various
bonds, coupled with the breakdown of
energy containing substrates , usually
ATP
 A+ B A- B
ATP ADP +ip
Example: synthetases
Carboxylases