Enhanced Stability of Glucoamylase Through Chemical Crosslinking

A series of bifunctional chemical modification reagents, presenting variations in both the chemistry of the functional groups and in the length of the spacer between the two reactive groups, have been evaluated as agents for enhancing the thermal stability of purified Aspergillus niger amyloglucosidase by means of intramolecular cross-linking. Several chemical modifiers (e.g., diimidoesters) were identified that more than double the half-life of this industrially important enzyme during incubation at 65°C in the absence of substrate. The increased stability of the modified enzymes has been correlated with changes in the fluorescence-monitored thermal denaturation curves of the modified enzymes, relative to that of the native enzyme.