Binding of a ligand to one subunit alters affinity at others, giving haemoglobin its sigmoidal oxygen curve.
Haemoglobin binding of the first oxygen shifts the structure from T (tense) to R (relaxed), raising the affinity for further oxygen, producing a sigmoidal curve. This allows nearly full loading in the lungs and efficient unloading in tissues.
The Bohr effect further reduces affinity at low pH or high CO2, delivering more oxygen to active tissue.
Binding of a ligand to one subunit alters affinity at others, giving haemoglobin its sigmoidal oxygen curve.
Cooperativity 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 Quaternary Structure, Michaelis-Menten Kinetics, Allosteric Regulation.
Myoglobin lacks cooperativity and has a hyperbolic curve.
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Cooperativity. Advanced topics assume the Intermediate vocabulary.
The closest topics to Cooperativity are Quaternary Structure, Michaelis-Menten Kinetics, Allosteric Regulation, Tertiary Structure. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Cooperativity. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
Cooperativity: Binding of a ligand to one subunit alters affinity at others, giving haemoglobin its sigmoidal oxygen curve. Quaternary Structure: The arrangement of multiple polypeptide subunits into one functional protein, such as haemoglobin. Read both side by side and note what each one explains.
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 Quaternary Structure and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.
The arrangement of multiple polypeptide subunits into one functional protein, such as haemoglobin.
⚗️ Biomolecules & BiochemistryModels reaction velocity as Vmax times substrate over Km plus substrate, describing enzyme saturation.
⚗️ Biomolecules & BiochemistryBinding of a molecule at a site other than the active site changes enzyme shape and activity.
⚗️ Biomolecules & BiochemistryThe overall three-dimensional shape of one polypeptide, held by side-chain interactions and disulfide bridges.
⚗️ Biomolecules & Biochemistry