NZY
NZYMES
MES
Amylase catalyses the breakdown
of starch
Amylase
Starch
Amylase
Maltose
Enzyme
Substrate
Enzyme
Product
The Lock and Key Mechanism of
Enzyme Action
In this diagram the enzyme breaks a large
molecule into smaller ones. The same enzyme
will also catalyse the reverse reaction – it will
join the smaller molecules together again.
The Induced Fit Hypothesis of
Enzyme Action
When the substrate binds to the enzyme’s
active site, it ‘induces’ a change of shape
so that the substrate and enzyme become
fully complementary.
A Graph To Show That The Activation Energy Of A
Reaction Is Smaller In The Presence Of An Enzyme.
DENATURATION
Don’t Forget!!!
Enzymes are Proteins and will show
a positive result with the Biuret test!
Cofactors
The Effect of Temperature on the Rate of
an Enzyme-Controlled Reaction
The Effect Of pH
The Effect Of pH on the Rate of
an Enzyme-Controlled Reaction
The Effect Of Changing Substrate
Concentration
The effect of changing the amount of substrate on the rate of an
enzyme-controlled reaction. As the amount of substrate increases from
0 to B, the rate of reaction increases. As the amount of substrate
increases from B to C, the rate of reaction does not increase any further.
Competitive Inhibitors
Non-Competitive Inhibitors
(ALLOSTERIC SITE)
The Effect of a Non-Competitive
Inhibitor
The effect of a non-competitive inhibitor on the rate of an enzymecontrolled reaction. The rate of reaction is always lower with a noncompetitive inhibitor, however much substrate is present.
End-Point Inhibition
By acting as an inhibitor, the end-product of a series of
reactions prevents its own production.
End-Point Inhibition continued…