Guuj

1. Subject Code –
Course-
Submited to –
Submited by -
Hygia Institute Of Pharmacy Approved By AICTE, PCI &
Affiliated To AKTU Prabandh Nagar, IIM Road, Lucknow-
226013
Topic-Regulation of
Enzyme
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2. CONTENTS
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3. Introduction
Regulation of enzyme activity is important to
coordinate different metabolic processes.
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4. Enzyms are regulated by
 Controlling their concentration
1. Control of synthesis (activation or repression)
2.Degradation
 Controlling the availability of substrate
1. Production, degradation, compartmentation of
substrate
2. Reversible binding of competitive inhibitors
 Controlling the activity of the enzyme
1. Reversible binding of modulators/effectors
2. Reversible or irreversible covalent modification
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5. Regulatory enzymes
 These are the enzymes (2 large groups) whose activity
can be changed in response to cell needs.
 Allosteric enzymes
 Enzymes regulated by reversible covalent modification
(reversible phosphorylation, reversible acetylation
and so on)
 There are enzymes which have properties of both groups
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6.  Allosteric enzymes contain two different sites:
the active site for catalysis
allosteric site for regulation
 The sites are located in distinct places of enzyme
molecule.
 Molecules that affect activity of an allosteric enzyme
bind to the allosteric site. These molecules are called
allosteric
effectors
Allosteric enzymes
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8. Kinetics of allosteric enzymes Effects of
allosteric effectors
 Cooperative effect in multimeric enzymes.
 In a case of allosteric enzyme, the dependence of the
reaction velocity against substrate concentration is S-
shaped curve.
 Homotropic allosteric effectors (activators) are substrate
molecules.
 Heterotropic allosteric effectors are molecules different
than substrates.
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9. Allosteric effectors
 Allosteric activators/ positive effectors: result in
increasing the reaction velocity and in increasing the
affinity of an allosteric enzyme to its substrate.
 Allosteric inhibitors / negative effectors: result in
decreasing the reaction velocity and in decreasing the
affinity of an allosteric enzyme to its substrate.
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10. Feed-back inhibition
 A sequence of enzymatic reaction with a
particular goat is considered as a
system/pathway of enzymes.
• Feed-back inhibition is a way ofregulation
of enzymatic system activity exerted via initial enzymes of
the system. Initial
enzymes usually are allosteric 10

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12. ANY QUERIES
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