In 1833, a French chemist Anselme Payen discovered the

first enzyme, diastase.

In 1877, German physiologist Wilhelm Kuhne, first used the term enzymes.

DISCOVERY OF ENZYMES

ENZYMES Enzymes are biological catalysts, mainly proteins,

generated by an organism to speed up chemical reactions.

They can be described as any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions.

Biological catalysts are those catalysts which are found in living organisms and they speed up the metabolic reactions occurring in them.

CATALYSTS A substance that lowers activation energy of a reaction

so the reaction occurs more quickly but, in the end, is not used up by the reaction is called a catalyst.

ACTIVATION ENERGY To start any chemical reaction, energy is required. The

minimum amount of energy required to start a reaction is known as it activation energy.

Activation Energy can be defined as the energy that must be added to cause molecules to react with one another.

Nomenclature of enzymeso An enzyme is named according to the name of the substrate it

catalyses.

o Some enzymes were named before a systematic way of naming enzymewas formed.

Example: pepsin, trypsin and rennin

o By adding suffix -ase at the end of the name of the substrate,enzymes are named.

o Enzyme for catalyzing the hydrolysis is termed as hydrolase.

Example :

maltose + water glucose + glucosemaltase

Nomenclature of enzymes

CHARACTERISTICS OF ENZYMES1. Structure

Enzymes are globular complex protein structures made up of long linear chains of amino acid ranging from just 62 amino acid residues in size to over 2,500 residues.

Most enzymes are much larger than the substrates they act on.

2. Reactions

Unlike most catalysts enzymes are NOT consumed by the reactions they catalyze.

During reactions only a small area is directly involved. This area is called active site.

• It is the region where the substrate is recognized and then bound for the reaction.

Active Site

• An enzyme substrate is the material upon which an enzyme acts.

Substrate

• A product is something "manufactured" by an enzyme from its substrate.

Product

3. Cofactors

There are some enzymes that need additional non protein molecules/ions called cofactors. Cofactors can be considered "helper molecules" that assist in biochemical transformations.

Cofactor

Organic

Prosthetic Group: tightly packed

Coenzyme: loosely attached

Inorganic

4. Metabolic Pathways

When enzymes work together metabolic pathways are formed. In metabolic pathways a chain or path of reactions is formed.

5. Inhibitors

Inhibitors are molecules that decrease enzyme activity. Many drugs and poisons are enzyme inhibitors.

Some types of inhibitors are given here:

Competitive :Substrate and inhibitor compete for the enzyme.

Uncompetitive :The inhibitor cannot bind to the free enzyme, only to the ES-complex.

Non-competitive : can bind to the enzyme at the binding site at the same time as the substrate, but not to the active site.

6. Activators

Activators have the opposite effect on enzymes. They are the molecules that increase enzyme activity.

WHAT FACTORS AFFECT ENZYMES?Enzymes are specific about the working conditions they are provided.

Changes in the working conditions can change the type of enzyme, its active site or its speed.

Some of the factors affecting enzyme activity are discussed here:

1. Temperature

2. pH

3. Substrate Concentration

1. Temperature

Every enzyme works at its best when given a specific temperature. This temperature is called the optimum temperature of that enzyme.

The optimum temperature of human enzyme is 37°C.

Reactions are accelerated when the temperature rises to a certain limit .But when this limit is crossed denaturation of enzymes takes place.

Rat

e o

f R

eact

ion

Temperature

0 20 30 5010 40 60

40oC - denatures

5- 40oC Increase in Activity

<5oC - inactive

2. pH

Optimum pH is the range of pH at which enzymes work best.

A slight change in this optimum pH causes:

i).retardation in enzyme activity.

ii).blockage of enzymes.

iii).ionization of amino acids at the active sites.

pH affects the formation of hydrogen bonds and

sulphur bridges in proteins and so affects shape.

pepsintrypsin arginase

2 4 8 106pH

Rat

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f R

eact

ion

(M

)

Acidic Basic

3. Substrate Concentration

If enzyme molecules are available in a reaction, increase in substrate concentration causes increase in the rate of reaction.

If the ratio of enzymes is less than the ratio of substrates then the enzymes enter a state called saturation of active sites.

HOW ENZYMES REACT? Lock and Key Model:

The enzyme and substrate are specific to each other. The active site of an enzyme fits together with a substrate like a lock and key. The key is the substrate and the lock is the enzyme.

Induced Fit Model:

The enzyme is induced to undergo a slight alteration in order to fit with the substrate perfectly.

SOME INDUSTRIAL APPLICATIONOF ENZYMES

Enzymes are produced in living organisms by cells but the enzymes used for commercial purposes are synthetic and made in industries.Enzymes are used in:1.Bread production.

2.Fermentation.

3. Paper production.

4.Production of cleaning products (detergent etc.)

Some Enzymes And Their Applications

APPLICATION ENZYMES USED

Food processing Amylase,Protease

Baby food Trypsin

Brewing industry Amylase,Protease

Fruit juices Cellulase,Pectinases

Dairy industry Lipases,Lactases

Paper industry Amylase,Ligninase, Xylanases,Cellulases

Biological detergent Amylase,Lipase,Cellulases

Rubber industry Catalase

Photographic industry Protease

ENZYMES AND THEIR USES IN THE BODY

ENZYMES USES IN MEDICAL

Foundation of energy

Life force in all living things

Help in thinking, moving, healing, reproducing,

growing etc…

Speed up all biochemical

reactions

Without enzymes, life won’t exist.

IMPORTANCE OF ENZYMES IN OURLIVES