Enzyme Activity Assays

Enzyme activity assays measure the functional activity of a therapeutic product. When a product's mechanism of action (MOA) is enzymatic, this assay serves as the primary potency test—a Critical Quality Attribute (CQA) that links the physical product to its intended biological effect. The core principle is to quantify the rate at which the enzyme converts a specific substrate into a measurable product. This rate is proportional to the concentration of the active enzyme under defined assay conditions and can be monitored through colorimetric, fluorescent, or luminescent signals. In some cases, more specific analytical techniques such as chromatography or mass spectrometry may be used to directly quantify substrate depletion or product formation, thereby confirming enzymatic activity.