Multiple co-interactions of different parameters on the functional properties of immobilized lipases.

In order to determine possible co-interactions between enzyme-support effects, and the influence of enzyme-enzyme interactions on their effects on the final enzyme properties, lipase B from Candida antarctica was immobilized on different supports, initially immobilized via interfacial activation, at low and saturating enzyme loadings. The used supports were octyl, amino-hexyl-, and the heterofunctional ones obtained by modification with divinyl sulfone, (blocking agents used were ethylenediamine or Gly). The different biocatalysts activities were analyzed using p-nitro phenyl butyrate, triacetin and R and S methyl mandelate. The comparison of the biocatalyst as a function of the activity depended on the utilized substrate. In some instances, the effects of the enzyme-enzyme interactions were reflected by the increase in specific enzyme activity (even by a factor over 3). Regarding the stability, the support and the enzyme loading defined this, and all changed when comparing the stabilities of the biocatalysts in phosphate or Tris, where depending on the enzyme loading the most stable biocatalysts could be either one or the other. Fluorescence studies suggested (mainly intensity at the maximal emission wavelength) that the enzymes present different conformations and that the inactivation on Tris and phosphate follows different pathways, and this also depended on enzyme loading.