Viscometric Measurement of Protease Activities on Gelatine Substrate

Abstract

The knowledge of enzymatic activity is necessary in many industrial processes. The common measurement techniques are time-consuming and therefore cost-intensive. Measurements of viscosities are a promising approach as a fast and cheap testing method. The major challenges are to find a suitable substrate with Newtonian flow behavior throughout the whole testing range as well as a correlation between viscosity of the solution and the decomposed mass. Water based gelatine-buffersystem as substrate is tested extensively regarding the dependence on different solvents, pH-values and gelatine batches. All viscosity measurements are performed with a rotational viscometer. It is shown that the gelatine-buffer-system is independent of the given parameters and found to fulfill the said requirements. A correlation model based on the Martin equation and necessary assumptions are presented. The required parameters intrinsic viscosity and Martin parameter can be derived by few measurements with little effort. The digesting enzyme Trypsin is used as model enzyme in the degradation experiments. The enzyme concentration is varied and the decrease of the viscosity is measured. A dependency between the enzyme concentration and the enzymatic activity or respectively the viscosity decrease is observed.

Keywords

• enzyme activity measurement
• protease
• trypsin
• gelatine
• intrinsic viscosity
• rotational viscometer
• martin equation
• correlation model
• degradation of gelatine solution