The activity and stability of â-lactamase from Citrobacter divers ULA-27 have been investigated in the presence of different ionic and zwitterionic surfactants. All the sulfobetaine surfactants tested allow the enzyme to retain its full activity, but the best stabilizing effect is greatly dependent on their structure. Very little variations on the monomer head group can significantly reduce enzyme deactivation or speed up the loss of activity with respect to buffer alone. The whole hydrophobic/hydrophilic balance on the head group seems to have a determining role in preserving â-lactamase activity and structure. The presence of zwitterionic surfactants stabilizes the protein conformation toward denaturation by urea and low-temperature inactivation. Similar experiments were performed in the presence of other two zwitterionic surfactants, an amine oxide, dimethylmyrisrtylamine oxide (DMMAO) and a carboxybetaine, cetyldimethylammonium methanecarboxylate (CB1-16). The former stabilizes the enzyme even better than the sulfobetaines, the latter quickly deactivates it. Therefore, the factors responsible for â-lactamase stabilization are dependent not only on the zwitterionic nature of the surfactant headgroup but also specific interactions between the surfactant and the protein may be important.
Influence of sulfobetaines on stability of the Citrobacter Diversus ULA-27 beta-Lactamase
DI PROFIO, Pietro;GERMANI, Raimondo;SAVELLI, Gianfranco
2001
Abstract
The activity and stability of â-lactamase from Citrobacter divers ULA-27 have been investigated in the presence of different ionic and zwitterionic surfactants. All the sulfobetaine surfactants tested allow the enzyme to retain its full activity, but the best stabilizing effect is greatly dependent on their structure. Very little variations on the monomer head group can significantly reduce enzyme deactivation or speed up the loss of activity with respect to buffer alone. The whole hydrophobic/hydrophilic balance on the head group seems to have a determining role in preserving â-lactamase activity and structure. The presence of zwitterionic surfactants stabilizes the protein conformation toward denaturation by urea and low-temperature inactivation. Similar experiments were performed in the presence of other two zwitterionic surfactants, an amine oxide, dimethylmyrisrtylamine oxide (DMMAO) and a carboxybetaine, cetyldimethylammonium methanecarboxylate (CB1-16). The former stabilizes the enzyme even better than the sulfobetaines, the latter quickly deactivates it. Therefore, the factors responsible for â-lactamase stabilization are dependent not only on the zwitterionic nature of the surfactant headgroup but also specific interactions between the surfactant and the protein may be important.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
