The document is a seminar presentation on the classification of enzymes submitted by Alka Kumari to Dr. Meenakshi Singh. It summarizes that enzymes are proteins that act as biological catalysts and almost all enzymes are essential to life. It then describes the six main classifications of enzymes recommended by IUBMB based on their catalyzed reactions: 1) oxidoreductases that catalyze oxidation-reduction reactions, 2) transferases that transfer chemical groups, 3) hydrolases that catalyze hydrolysis reactions, 4) lyases that cleave bonds without hydrolysis or oxidation, 5) isomerases that catalyze structural changes, and 6) ligases that join chemical groups using ATP energy.

1. PATNA UNIVERSITY
DEPARTMENT OF BOTANY
A SEMINAR PRESENTATION ON
“ CLASSIFICATION OF ENZYMES”
SUBMITTED TO: SUBMITTED BY:
Dr. MEENAKSHI SINGH ALKA KUMARI
HOD, DEPARTMENT OF BOTANY ROLL NO.- 04
PATNA UNIVERSITY M.Sc. BOTANY
SEMESTER –II
SESSION: 2020-22

2. ENZYMES
 Enzymes are proteins that functions as
biological catalysts. A catalyst is a substance
that speeds up a chemical reaction but isn’t
changed by the reaction.
 Almost all enzymes are proteins and essential
to life.
 In enzymatic reactions, the molecules at the
beginning of the process are called substrates,
and the enzyme converts them into different
molecules, the products.

3. Classification of Enzymes
 Based on catalyzed reactions, the nomenclature
committee of the International Union of
Biochemistry and Molecular Biology(IUBMB)
recommended the following classifications:
1. OXIDOREDUCTASES
 Catalyze a variety of oxidation-reduction
reactions.
 Act on many chemical groups to add or remove
hydrogen atoms.
 The common name will be dehydrogenase,
reductase.

4. 2. TRANSFERASES
 Transfers chemical groups(acetyl, methyl,
phosphate etc.) from one molecule to another
or to another part of the same molecules.
 Kinases are specialized transferases that
regulate metabolism by transferring phosphate
from ATP to other molecules.

5. 3. HYDROLASES
 Catalyzes hydrolysis reactions where a
molecule is split into two or more smaller
molecules by the addition of water.
 PROTEASES split protein molecules
 HIV Protease is essential for HIV replication
 Caspase plays a major role in apoptosis
 NUCLEASES split nucleic acids(DNA and RNA)
 Based on the substrate type , they are divided
into RNase and DNase.

6. 4. LYASES
 Catalyzes the cleavage of C-C, C-O, C-S and C-
N bonds by means other than hydrolysis or
oxidation.
 Common names include decarboxylase and
aldolase.
5. ISOMERASES
 These enzymes catalyze geometric or structural
changes within one molecule.
 According to type of isomerism, they may me
called cis-trans isomerases, tautomerases etc.

7. 6. LIGASES
 Catalyze reactions in which two chemical groups
are joined(or ligated) with the use of energy from
ATP.
 Examples include peptide synthase, DNA ligase
and RNA ligase.