ENZYMES
Enzymos (Greek) : an agent that modify a whole
An enzyme is a biological catalyst, that increase the rate of a chemical reaction
without being consumed in the process.
The substance upon which an enzyme acts is called the substrate. The enzyme
will convert the substrate into product or products.
Characteristics of enzymes
Convert substrate into product.
Highly specific for their substrate.
They are colloidal in nature.
They are thermolabile.
They are protein in nature except ribozyme which contains RNA
They are water soluble.
They can be precipitated by protein precipitating reagents (ammonium
sulphate, trichloroacetic acid)
HOW ENZYMES WORK
Step 1:
Enzyme (E) + Substrate (S) <—–> Enzyme-Substrate complex (ES)
Step 2:
Enzyme-Substrate complex (ES) <—–> Enzyme (E) + Product (P)
The above two steps can be combined as follows to give the complete reaction.
Overall Reaction:
Enzyme (E) + Substrate (S) <—–> Enzyme-Substrate complex (ES) <—–>
Enzyme (E) + Product (P)
, The amino acids present in the active site of the enzyme give the enzyme a
definite shape. The shape uniquely determines its substrate and helps it to bind
and form the enzyme-substrate complex. The enzyme then converts the bound
substrate to a product with itself remaining chemically unchanged.
HOW ENZYMES SPEED UP REACTIONS?
Enzymes work by decreasing the activation energy, like all catalysts. Activation
energy is the amount of energy needed for the reaction to begin. They generally
lower the activation energy by reducing the energy needed for reactants to react
during a reaction. Lesser the activation energy of a reaction, the faster the rate
of the reaction.
They do so in the following ways:
Bring the reactants together such that they do not need to expend energy
moving about to collide.
Position the reactants correctly so that they do not have to overcome
intermolecular forces that would typically push them apart
Change the pathway so that the reaction can occur by the pathway with
lower activation energy.
After the reaction, the products formed are released from the active site of
the enzyme. The enzyme remains unaltered at the end of the reaction and thus is
free to bind another substrate and catalyze a new reaction.
Enzymos (Greek) : an agent that modify a whole
An enzyme is a biological catalyst, that increase the rate of a chemical reaction
without being consumed in the process.
The substance upon which an enzyme acts is called the substrate. The enzyme
will convert the substrate into product or products.
Characteristics of enzymes
Convert substrate into product.
Highly specific for their substrate.
They are colloidal in nature.
They are thermolabile.
They are protein in nature except ribozyme which contains RNA
They are water soluble.
They can be precipitated by protein precipitating reagents (ammonium
sulphate, trichloroacetic acid)
HOW ENZYMES WORK
Step 1:
Enzyme (E) + Substrate (S) <—–> Enzyme-Substrate complex (ES)
Step 2:
Enzyme-Substrate complex (ES) <—–> Enzyme (E) + Product (P)
The above two steps can be combined as follows to give the complete reaction.
Overall Reaction:
Enzyme (E) + Substrate (S) <—–> Enzyme-Substrate complex (ES) <—–>
Enzyme (E) + Product (P)
, The amino acids present in the active site of the enzyme give the enzyme a
definite shape. The shape uniquely determines its substrate and helps it to bind
and form the enzyme-substrate complex. The enzyme then converts the bound
substrate to a product with itself remaining chemically unchanged.
HOW ENZYMES SPEED UP REACTIONS?
Enzymes work by decreasing the activation energy, like all catalysts. Activation
energy is the amount of energy needed for the reaction to begin. They generally
lower the activation energy by reducing the energy needed for reactants to react
during a reaction. Lesser the activation energy of a reaction, the faster the rate
of the reaction.
They do so in the following ways:
Bring the reactants together such that they do not need to expend energy
moving about to collide.
Position the reactants correctly so that they do not have to overcome
intermolecular forces that would typically push them apart
Change the pathway so that the reaction can occur by the pathway with
lower activation energy.
After the reaction, the products formed are released from the active site of
the enzyme. The enzyme remains unaltered at the end of the reaction and thus is
free to bind another substrate and catalyze a new reaction.
