The native form of hemocyanin Hc. from Octopus Íulgaris can be completely dissociated, at alkaline pH and in thepresence of EDTA, from 49S decamers to 11S monomers. The kinetics of this process was studied, using a Bio-Logicstopped flow system, by following the time dependence of the 450-nm light intensity, scattered at 908, in the 7.9–8.8 pHrange. All experimental traces were best fitted by a sum of three exponential decay functions. We then tried to best fit thesedecay functions with a series of kinetic models, the best of them resulting in one whose dissociation of decamers tomonomers takes place in three consecutive and irreversible steps, with a highly cooperative step concerning dissociation ofoctamers to dimers, which appears to be the only intermediate species. This model was preferred over several others, notonly for the best norm value but also for the best accordance between each calculated and experimental kinetic parameterrate constants and amplitudes.. Although other more complex models may be considered, our best fit model represents thesimplest one, which is able to describe the observed dissociation kinetics.[...]
Dissociation kinetics of hemocyanins from Octopus vulgaris
DAINESE, Enrico;
1998-01-01
Abstract
The native form of hemocyanin Hc. from Octopus Íulgaris can be completely dissociated, at alkaline pH and in thepresence of EDTA, from 49S decamers to 11S monomers. The kinetics of this process was studied, using a Bio-Logicstopped flow system, by following the time dependence of the 450-nm light intensity, scattered at 908, in the 7.9–8.8 pHrange. All experimental traces were best fitted by a sum of three exponential decay functions. We then tried to best fit thesedecay functions with a series of kinetic models, the best of them resulting in one whose dissociation of decamers tomonomers takes place in three consecutive and irreversible steps, with a highly cooperative step concerning dissociation ofoctamers to dimers, which appears to be the only intermediate species. This model was preferred over several others, notonly for the best norm value but also for the best accordance between each calculated and experimental kinetic parameterrate constants and amplitudes.. Although other more complex models may be considered, our best fit model represents thesimplest one, which is able to describe the observed dissociation kinetics.[...]I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
