Summary
Binding of a molecule at a site other than the active site changes enzyme shape and activity.
In depth
Allosteric enzymes have multiple subunits and often show sigmoidal kinetics. Activators stabilise the active form (R state) and inhibitors the inactive form (T state).
This allows fine control at key regulatory steps of pathways.
Allosteric means other site. The classic example is aspartate transcarbamoylase, inhibited by CTP and activated by ATP. Binding of an effector shifts the equilibrium between T and R states, as described in the MWC model, while the sequential model proposes stepwise change.
Many drugs target allosteric sites, which can be more selective than active sites. Allosteric control is fast, reversible and requires no new protein, so it is used for quick responses such as in glycolysis, where phosphofructokinase is inhibited by ATP and citrate and stimulated by AMP.
Key idea: allosteric proteins act like switches or dimmers, with their set point adjustable by small molecules.
Frequently asked questions
What is Allosteric Regulation?
Binding of a molecule at a site other than the active site changes enzyme shape and activity.
Which area of biology covers Allosteric Regulation, and how advanced is it?
Allosteric Regulation is one of the 51 topics in Biomolecules & Biochemistry. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Protein Post-Translational Modification, Quaternary Structure, pH and Buffers.
Can you give an example of Allosteric Regulation?
Phosphofructokinase in glycolysis is inhibited by ATP and citrate and activated by AMP.
What should I learn before Allosteric Regulation?
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Allosteric Regulation. Advanced topics assume the Intermediate vocabulary.
What topics are related to Allosteric Regulation?
The closest topics to Allosteric Regulation are Protein Post-Translational Modification, Quaternary Structure, pH and Buffers, Feedback Inhibition. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Allosteric Regulation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Allosteric Regulation. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
How is Allosteric Regulation different from Protein Post-Translational Modification?
Allosteric Regulation: Binding of a molecule at a site other than the active site changes enzyme shape and activity. Protein Post-Translational Modification: Chemical changes such as phosphorylation, glycosylation and ubiquitination that regulate protein activity and fate. Read both side by side and note what each one explains.
How should I study Allosteric Regulation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Protein Post-Translational Modification and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.