Classification and Nomenclature of Enzymes

Introduction - In earlier days enzymes were called by some ambiguous and uninformative name such as – ptyalin, zymase, trypsin, errosion etc. Later their name are done by the addition of suffix 'ase' after the name of the substrate on which they act.

Types of Enzymes - There are different types of enzyme according to their reaction and catalytic power International Union of Biochemistry divided into six major groups. This groups are follows -

1. Oxidoreductase - This type of enzymes are associated with the oxidation reduction reaction. This enzymes are of two types . They are – (i) Oxidase (ii) Dehydrogenase.

(i) Oxidase - This type of enzymes causes addition of oxygen to the substrate. Examples of this enzymes are amino acid oxidase, cytochrome oxidase etc.

(ii) Dehydrogenase - This type of enzyme remove hydrogen from the substrate. Examples of this type of enzymes are succinic dehydrogenase, malic dehydrogenase etc.

Other type of enzymes are reductase which is associated with the reduction of the substrate by addition of hydrogen atoms to the substrate. Examples of the reductase are retinene reductase.

Mechanism of Enzyme Oxidoreductase

2. Transferase - Transferase are group of enzymes that transfer specific functional group from one substrate to the other substrate. Examples of this group of enzymes are amino transferase, hexokinase, Cholin acetylase etc.

3. Hydrolases - This group of enzymes are associated with the hydrolytic reaction of compound. Examples of this group are amylase, peptidase,lipase etc. These enzymes causes breakdown of larger molecules into smaller ones by addition of water molecules and split off specific co valent bond. This process is called hydrolysis.

4. Lyases - This group of enzyme causes removal of groups from the substrate or addition of group to the substrate. This is occurred by the process called hydrolysis, oxidation, reduction etc. Examples of this enzymes are – Carboxylase, fumarase, agrinosuccinase, decarboxylase etc.

Mechanism of Lyases


5. Isomerase - Enzymes of this group are associated with the conversion of isomers. Examples are Phosphohexose isomerase, triose phosphate isomerase.

Mechanism of Isomerase

6. Ligase or Synthetase or Synthase - In this group of enzyme ,it catalyses linking of two compounds by energy requiring reactions. Examples of this type of enzymes are glycogen Synthase, fatty acid synthase etc.

Nomenclature of the Enzyme - According to the international system of enzyme classification- Name of an enzyme is considered both the substrate on which it acts and the type of reaction it catalyses.

Here first will be the name of the substrate and the second part will be the type of reaction it catalyses.

The ending of the enzyme name will be with ‘ ase’ .

Nomenclature explain with example- lactic dehydrogenase is an enzyme . Whose first part is formed from lactic acid as it acts as substrate and this enzyme is associated with dehydrogenation means oxidation . Thus the second part of the enzyme name dehydrogenase (as -ase will be added to the end).


Questions and Answers on Classification and Nomenclature of Enzymes:

1.What is the function of lipase?

Lipase splits lipid.


2. What does protease do?

It splits the protein.


3. What is the role of amylase?

This enzyme splits the amylum or starch.

You might like these



Eleventh Grade

From Factors Affecting Enzyme Activity to HOME PAGE

New! Comments

Have your say about what you just read! Leave me a comment in the box below.


Recent Articles

  1. Amphibolic Pathway | Definition | Examples | Pentose Phosphate Pathway

    Jun 06, 24 10:40 AM

    Amphibolic Pathway
    Definition of amphibolic pathway- Amphibolic pathway is a biochemical pathway where anabolism and catabolism are both combined together. Examples of amphibolic pathway- there are different biochemical…

    Read More

  2. Respiratory Balance Sheet | TCA Cycle | ATP Consumption Process

    Feb 18, 24 01:56 PM

    ATP Synthase in Mitochondria
    The major component that produced during the photosynthesis is Glucose which is further metabolised by the different metabolic pathways like glycolysis, Krebs cycle, TCA cycle and produces energy whic…

    Read More

  3. Electron Transport System and Oxidative Phosphorylation | ETC |Diagram

    Feb 04, 24 01:57 PM

    Electron Transport Chains
    It is also called ETC. Electron transfer means the process where one electron relocates from one atom to the other atom. Definition of electron transport chain - The biological process where a chains…

    Read More

  4. Tricarboxylic Acid Cycle | Krebs Cycle | Steps | End Products |Diagram

    Jan 28, 24 12:39 PM

    Aerobic Respiration
    This is a type of process which execute in a cyclical form and final common pathway for oxidation of Carbohydrates fat protein through which acetyl coenzyme a or acetyl CoA is completely oxidised to c…

    Read More

  5. Aerobic Respiration | Definition of Aerobic Respiration | Glycolysis

    Dec 15, 23 08:42 AM

    Aerobic Respiration
    This is a type of respiration where molecular free oxygen is used as the final acceptor and it is observed in cell. Site of Aerobic Respiration - Aerobic respiration is observed in most of the eukaryo…

    Read More