Ion-Specific Protein/Water Interface Determines the
Hofmeister Effect on the Kinetic Stability of Glucose Oxidase
Erik Sedlák
Dagmar Sedláková
Jozef Marek
Jozef Hančár
Katarína Garajová
Gabriel Žoldák
10.1021/acs.jpcb.9b05195.s001
https://acs.figshare.com/articles/journal_contribution/Ion-Specific_Protein_Water_Interface_Determines_the_Hofmeister_Effect_on_the_Kinetic_Stability_of_Glucose_Oxidase/9805352
Homodimeric glucose
oxidase (GOX) from Aspergillus
niger is a prominent enzyme used for a number of applications
in biotechnology and clinical diagnostics. For robust and long-term
functional applications of GOX, the stability of the protein is of
utmost importance. In vitro, GOX is irreversibly inactivated over
time by a mechanism that is poorly understood, and hence, it presents
a significant drawback for the development of strategies to stabilize
the enzyme. We show that the nonequilibrium stability of GOX is fully
described by a one-step conformational unfolding kinetics. To explore
the strategies for improving GOX nonequilibrium stability, the effect
of salts of the Hofmeister series is examined using microcalorimetry.
We obtain activation energies <i>E</i><sub>a</sub> and inactivation
temperatures <i>T</i><sub>k</sub> (at which the irreversible
step is 1.0 min<sup>–1</sup>) as a function of the salt types
and concentrations. Based on the analysis by the extended Langmuir
model, we find that at high salt concentrations (>1 M) the Hofmeister
effect on inactivation temperature is determined by the universal
ion-specific effect on the protein/water interface, which apparently
does not depend significantly on a particular amino-acid sequence
and 3D protein structure. Our findings identify protein/water interfacial
tension as a critical physicochemical attribute of excipients that
is crucial for increasing enzyme kinetic stability.
2019-09-11 14:44:49
inactivation temperatures T k
enzyme
Kinetic Stability
ion-specific effect
salt types
Hofmeister series
amino-acid sequence
inactivation temperature
Glucose Oxidase Homodimeric glucose oxidase
strategy
GOX nonequilibrium stability
Hofmeister effect
Aspergillus niger
3 D protein structure
concentration
activation energies E
application
nonequilibrium stability
Hofmeister Effect
Langmuir model