The effect of chemical crosslinking of invertase with dimethyl suberimidate on its pH stability

The effect of chemical crosslinking of invertase with a homo-bifunctional bisimidoester on its pH stability was studied. Dimethyl suberimidate (DMS) was used as the crosslinker and pH inactivation was investigated in the pH range of 2.5-10. The inactivation mechanisms of both native and DMS crosslinked invertases were observed to follow first-order kinetics during prolonged incubation. Although DMS crosslinking of invertase increased the pH stability of the enzyme over the complete pH range, it was especially effective over the acidic range. The half-lives of invertase increased almost twofold, on average, by crosslinking at the neutral to the acidic range. The effect of crosslinking was especially pronounced at pH 5 since both the half-life of the native invertase and the stabilization factor were very high. Higher activation free energies of inactivation were obtained for DMS crosslinked invertases over the whole pH range which also indicates the stabilization of invertase by crosslinking.