Performance of an immobilized recombinant leucine aminopeptidase after storage in ethanol–water solution

AbstractImmobilized enzymes offer different benefits such as the feasibility to be reused for reproducible bioprocesses. The challenge is to establish the appropriate storage conditions that allow the maintenance of their properties for long periods. In this study, we immobilized a recombinant leucine aminopeptidase (I-rLAP) on a siliceous support synthesized from tetraethyl orthosilicate (TEOS) activated with glutaraldehyde to evaluate its residual activity after storage in 20% v/v ethanol and sodium azide solutions at 4 and 25 °C. The characterization of the support by X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT) and field emission probe microanalyzer (EPMA) was consistent with previous characterization reports of silica gel matrices. Particle size ≤420 μm exhibited a suitable performance that avoided high backpressure into the columns and increased the amount of immobilized enzyme. I-rLAP recovered up to 90% of the applied activity after 64 days of storage at 4 and 25...