Cooperative binding

Cooperative binding is when the number of small molecules binding to a macromolecule depends on the concentration of those small molecules around the macromolecule.Heinz Decker & Kensal E van Holde 2011. Oxygen and the evolution of life Heidelberg; New York: Springer, p. 84

This is a type of molecular binding, which is where molecules attach to each other in a stable way without decaying or breaking that bond rapidly. 

 Example 
A popular example of cooperative binding is between hemoglobin and oxygen.Michael L Johnson; Jo M Holt; Gary K Ackers 2011. Biothermodynamics, Part D Amsterdam, Netherlands; Boston, MA: Elsevier/Academic Press, p. xiii In the lungs, there is a very high concentration of oxygen in the alveoli of the lungs. So the oxygen bonds to haemoglobin to form oxyhaemoglobin.Pamela C. Champe; Richard A. Harvey; Denise R. Ferrier 2005. Biochemistry Philadelphia: Lippincott Williams & Wilkins, p. 29 When this travels around the body in the blood and reaches areas of low oxygen concentration, the oxygen is released from the haemoglobin.Pauling L. 1935. The oxygen equilibrium of hemoglobin and its structural interpretation. Proceedings of the National Academy of Sciences of the United States of America 21 (4): 186–191.  

 References 

 Other websites 
Khan Academy-Haemoglobin

Category:Biochemistry