Enzymes Inhibitors

Enzymes are globular proteins there main function is to reduce the activation energy (The minimum energy required to initiate a reaction) and speed up of a biochemical reaction but in nature some molecules are present which inhibit(effect) the enzymes activity called as Inhibitors.

INHIBITORS:

Defined as *The molecules which effect enzyme activity and make enzyme inactive called as inhibitors*

*The molecules bind with enzymes but are not converted into suitable product are called Inhibitors or Enzyme inhibitors*.

The completely stop a rate of reaction but sometimes they just slow down rate of reaction.

Inhibitors are present in both forms naturally and artificially.

ENZYME INHIBITION:

The phenomenon in which enzymes fails to catalyze a reaction called as Enzyme inhibition.

In general enzyme inhibition is normal process in cells to regulate enzyme activity but when external factors cause enzyme inhibition then it is dangerous for life.

There are two types of inhibitors which are explained below;

1-COMPETITIVE INHIBITOR:

The type of enzyme inhibition in which enzyme activity is blocked temporarily by the presence of a chemical that compete with substrate for binding to the active site is called competitive inhibition and molecules are called competitive inhibtors.

Competitive inhibitors are actually molecules that have same structure like substrate and they compete with substrate for active site of an enzyme and when they bind with enzyme they deactivate the enzyme.

It is actually temporary process because when we used high concentration of substrate this inhibition process reverse and blocked enzyme become active again and this process is called REVERSIBLE INHIBITION.

Competitive inhibitors are also called as REVERSIBLE INHIBITORS.

EXAMPLE:

The perfect example of competitive inhibitors is malonate.

Succinate dehydrogenase that catalyzes the formation of fumarate from succinate is completely blocked by malonate.

The by product of sulphonamide drug also act as competitive inhibitors.

IMPORTANCE OF COMPETITIVE INHIBITORS:

1-They used as drugs in the control of bacterial pathogens.

2-They support lock and key hypothesis.

3-Antibiotics like sulphonamide which acts competitive inhibitors are used to combat bacterial infection.

4-It shows the substances that are similar to substrate are not acted by enzymes.

2-NON COMPETITIVE INHIBITORS:

The molecules which are different from substrate and binds with enzymes on site other than active site and alter the shape of enzyme and deactivate the enzyme called as non competitive inhibitors.

It attacks on allosteric site (The framework of whole enzyme except active site) of an enzyme.

The non competitive inhibitors inactivate the enzyme temporarily or they denature enzymes permanently on this base non competitive inhibitors are divided into two types.

A-REVERSIBLE NON COMPETITIVE INHIBITORS:

They allow formation of enzyme substrate complex but prevent formation of enzyme product complex.So they just prevent formation of product therefore named as reversible non competitive inhibitors.

EXAMPLES:

Feedback inhibition is an example of reversible non competitive inhibitors.

B-IRREVERSIBLE NON COMPETITIVE INHIBITORS:

The molecules that binds with alloesteric site of an enzyme tightly and alter the shape of enzyme permnently and make enzyme inactive permanently.

EXAMPLES:

Cyanides , Heavy metal ions(Ag+,Hg++ and Cu++) and some insecticides are act as Irreversible non competitive inhibitors.