As biocatalysts, enzymes control thousands of reactions that enable energy conversion, synthesis and metabolic degradation. Reduced or increased enzyme activity can lead to a disturbed balance at the cellular level, which manifests as a disease state at the organism level. One of these disease states that is directly related to the lack of enzyme activity is hypolactasia or lactose intolerance. In humans, it occurs due to reduced enzyme activity of β-galactosidase (lactase), an enzyme that breaks down the disaccharide lactose into monosaccharide components. To alleviate the symptoms, patients take dietary supplements whose active ingredient is the enzyme β-galactosidase. The central topic of the experimental work was the investigation of the enzymatic activity of β-galactosidase from two different organisms E.coli (β-Gal-E) and Asp.oryzae (β-Gal-A). In the experiments, we also used β-galactosidase (Asp.oryzae) isolated from a commercially available dietary supplement (β-Gal-P). We were interested in the influence of temperature, pH, enzyme and substrate concentrations on β- galactosidase activity in the presence of o-nitrophenil-β-D-galactopiranoside. In experiments using X-gal as substrate, the effect of temperature and enzyme concentration on the amount of colored product formed was observed colorimetrically. Through experiments, we have confirmed that increasing values of the temperature of the reaction mixture or the concentration of the enzyme increase the amount of product formed or enzyme activity. β-Gal-A and β-Gal-P reached maximum values of enzyme activity at pH 5, and β-Gal-E enzyme at pH 7.4. Based on the experiments, we prepared instructions for conducting laboratory exercises that enable cross-curricular integration of biology and chemistry knowledge. The first set of prepared experiments focuses more on understanding the effects on the enzymatic activity of β-galactosidase and the use of the spectrophotometer, while the second set focuses on the analytical method used and the construction of the colorimeter, which can serve as a prototype for understanding the operation of other spectroscopic methods.
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