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.