Effect of Electrolyte Ions on the Stability of Flavin Adenine Dinucleotide‐Dependent Glucose Dehydrogenase

Abstract

The thermal stability of flavin adenine dinucleotide‐dependent glucose dehydrogenase (FAD‐GDH) from Aspergillus terreus in phosphate buffer solution was substantially improved by kosmotropic ions, especially kosmotropic anions. The residual activity of FAD‐GDH in a 1.5 M sodium or ammonium sulfate solution remained more than 90 % after 60 min of heat treatment at 60 °C, while slight activity was observed for FAD‐GDH in a solution in the absence of additive sulfate ions. The stabilizing effect of the electrolytes was concentration‐dependent and strongly related to the structural stabilization of the enzyme, which involved enzyme compaction.