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active site no longer
Noncompetitive inhibitor Figure 8.19 (c) Noncompetitive inhibition • Concept 8.5: Regulation of enzyme activity helps control metabolism
• A cell’s metabolic pathways
• Must be tightly regulated Allosteric Regulation of Enzymes
• Allosteric regulation • Is the term used to describe any case in which a protein’s function at one site is affected by binding of a regulatory molecule at another site
• Noncompetitive inhibition is a form of allosteric regulation • They change shape when regulatory molecules bind to specific sites, affecting function
with four subunits Regulatory
of four) Active site stabilizes active from
(one of four) Activator
Stabilized active form Oscillation Allosteric activater
stabilizes active form NonInactive form Inhibitor
site Figure 8.20 Stabilized inactive
form (a) Allosteric activators and inhibitors. In the cell, activators and inhibitors
dissociate when at low concentrations. The enzyme can then oscillate again. • Cooperativity • Is a form of allosteric regulation that can amplify enzyme activity Binding of one substrate molecule to
active site of one subunit locks
all subunits in active conformation. Substrate Inactive form Figure 8.20 Stabilized active form (b) Cooperativity: another type of allosteric activation. Note that the
inactive form shown on the left...
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This note was uploaded on 11/09/2011 for the course BIO 181 taught by Professor Staff during the Summer '10 term at Chandler-Gilbert Community College.
- Summer '10