This document introduces enzymes and discusses their catalytic activity, protein nature, types (monomeric and oligomeric), specificity, and models of enzyme-substrate complex formation. Enzymes are proteins that act as catalysts in biological systems, increasing the rate of reactions without being used up. They have sites that substrates fit into, and can lower the activation energy of reactions. The induced fit model proposes that enzyme active sites are flexible and change shape to better accommodate substrates.

1. INTRODUCTION OF ENZYMES
&
MODELS ENZYME SUBSTRATE
COMPLEX FORMATION

2. PRESENTED BY:
Muhammad Arshad Malik
MBBS First Year
Hashmat Medical College

3. WHAT ARE ENZYMES?
• Catalyst of biological system
• Protein in nature
• Increase the rate of reaction without being used

4. CATALYTIC ACTIVITY OF ENZYMES
• Enzymes have immense power to accelerate the ate of reaction
by reducing activation energy
• Activation energy is the minimum amount of energy required to
start the chemical reaction.
• It can be decreased by increasing the temperature of reaction
medium

5. PROTEIN NATURE OF ENZYME
• All enzymes are proteins in nature having large molar weight
• Few enzyme are simple proteins while some are conjugated proteins
in nature
• Enzymes are consist of two parts: protein part and non protein part.
• Protein part is called Apo enzyme while non protein is called co
enzyme or prosthetic group
• Combination of apoenzyme and co enzyme is called holoenzyme

6. MONOMERIC ENZYME & OLIGOMERIC
ENYMES
• Monomeric enzymes consist of one polypeptide chain
• Example ribonuclease
• Oligomeric enymes are consist of more than one poly peptide
chains
• Example hexokinase
• Single chain of oligomeric enzyme is called subunit

7. SPECIFITY OF ENZYME
• Optical specifity
• There can be many optical isomers of substrate but only one of
the isomers act as substrate for enzyme action
• Reaction specifity
• One enzyme can catalyze specific reaction only
• E.g. oxaloacetic acid can undergo many reation sbut each
reaction is catalyze by specific enzyme

8. MODEL OF ENZYME SUBSTRATE COMPLEX
• There are two modals enzyme substrate complex
• Lock and key modal
• Active site is rigid and preshaped. Substrate fits into active site
of enzyme like key fits into lock.
• This modal is not accepted because it is unable to explain
changes in enzyme activity.

9. MODEL OF ENZYME SUBSTRATE COMPLEX
• Induce fit modal
• According to this modal, active site is not rigit. It is flexible in
nature. When substrate fits into active site of enzyme, it
produce changes in active site structure.

10. Thanks You All