On the Relationship Between the Hill Coefficients for Steady-state and Transient Kinetic Data: A Criterion for Concerted Transitions in Allosteric Proteins
✍ Scribed by Amnon Horovitz; Ofer Yifrach
- Publisher
- Springer
- Year
- 2000
- Tongue
- English
- Weight
- 61 KB
- Volume
- 62
- Category
- Article
- ISSN
- 1522-9602
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✦ Synopsis
A frequently used measure for the extent of cooperativity in ligand binding by allosteric proteins is the Hill coefficient. Hill coefficients can be measured for steady-state kinetic data and also for transient kinetic data. Here, the relationship between the two types of Hill coefficients is analysed. It is shown that a value of 1 for the ratio of the two Hill coefficients is a test for a concerted ligand-induced transition between two conformations of the protein, in accordance with the Monod-Wyman-Changeux model. A value of 1 for this ratio has recently been observed for a series of chaperonin GroEL mutants suggesting that ATP-induced allosteric transitions in this protein are concerted.