COMPARISON OF THE ADSORPTION AND ACTIVITY OF LIPASES FROM HUMICOLA-LANUGINOSA AND CANDIDA-ANTARCTICA ON SOLID-SURFACES

The adsorption of lipases from Humicola lanuginosa-the wild type (WT) and a mutant with increased hydrophobicity in the active site region-a nd Lipase B from Candida antarctica to solid surfaces was studied by i n situ ellipsometry. In addition, the activity of the adsorbed lipase was measured in situ and from the different surface concentrations, th e specific activity was calculated. Concentration and temperature depe ndence as well as the influence of surface wettability was studied usi ng silica surfaces with varying degree of methylation The higher hydro phobicity of the mutant compared to the WT resulted in increased amoun ts adsorbed, no desorbable fraction during rinsing and absence of an i nitial maximum in adsorbed amount (as seen for the WT) at higher conce ntrations. No temperature dependence for the mutant could be observed. This was in contrast to the WT where both the plateau value of the ad sorbed amount and the activity decreased with increasing temperature. The influence of surface wettability was similar for both featuring a decreased adsorbed amount and increased specific activity with increas ing wettability. The amount adsorbed of the Candida lipase was signifi cantly higher at all concentrations, compared to the other lipases, an d the activity was very low, indicating adsorption with the active sit e region directed toward the surface. The surface wettability did not affect the activity of the Candida lipase.