Adsorption and activation of zymogens at solid-liquid interfaces. I. Chymotrypsinogen on alkylamino modified silica...

Silica beads were modified with alkylamino groups of different lengths (C2, C4, C6, C8, and C10) and hydrophobicity. The relationship between surface structure and adsorption of chymotrypsinogen followed by its activation with trypsin at the solid-liquid interface was studied. From the adsorption isotherms, it follows that underivatized silica adsorbed chymotrypsinogen (CTG) well. The adsorption of CTG on alkylamino modified silicas appeared to correlate with the hydrophobicity of the latter. The longer the alkyl chains were, the higher was the amount of adsorbed CTG. The activation of adsorbed CTG with trypsin at the solid-liquid interface was a slower process when compared with the activation conducted in solution. Parallel experiments were performed with chymotrypsin (CT). The adsorption behavior was similar to that of CTG. The activity of adsorbed CT was inversely proportional to the hydrophobicity of the beads. These results correlated well with the desorption of CT after repeated washings. Repeated addition of substrate (Gly-Gly-Phe-NAp) to the CT covered beads resulted in the CT desorption. The higher the hydrophobicity of the beads was, the lower was the desorption of CT.