| Autor: |
Brittain, T, Hofmann, O M, Watmough, N J, Greenwood, C, Weber, R E |
| Jazyk: |
angličtina |
| Rok vydání: |
1997 |
| Předmět: |
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| Zdroj: |
Brittain, T, Hofmann, O M, Watmough, N J, Greenwood, C & Weber, R E 1997, ' A two-state analysis of co-operative oxygen binding in the three human embryonic haemoglobins ', Biochemical Journal, vol. 326 ( Pt 2), pp. 299-303 . |
| Popis: |
Udgivelsesdato: 1997-Sep-1 The binding of oxygen to the three human embryonic haemoglobins, at pH 7.4, has been shown to occur as a co-operative process. Analysis of oxygen-binding curves obtained in the absence of organic phosphate allosteric effectors shows that the process can be described quite accurately by the two-state model of allosteric action. In the presence of organic phosphates, the binding affinity for oxygen to the T-state of the alpha 2 epsilon 2 and zeta 2 epsilon 2 haemoglobins is significantly lowered. The values of the best-fit two-state parameters determined for each of the embryonic haemoglobins together with the temperature-dependence of the overall equilibrium binding process are discussed in terms of oxygen transfer from the maternal blood supply. Fast-reaction studies have been used to determine the rate constants of the oxygen association and dissociation processes occurring in the R-state and the rate of the allosteric R > T conformational transition. Analysis of these data suggests a likely reason for the high affinity and low co-operativity of the embryonic proteins and identifies the origins of the inability of equilibrium measurements to identify chain non-equivalence in the R-state. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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