Which method is NOT commonly used to measure enzymatic activity?

Electrophoresis, while a powerful technique for separating and analyzing proteins and nucleic acids based on size and charge, is not typically used to measure enzymatic activity directly. This method focuses more on analyzing the properties of enzymes rather than quantifying their functional activity.

In contrast, spectrophotometry is commonly employed to measure enzymatic activity by detecting changes in absorbance related to substrate or product concentrations as reactions proceed. Similarly, fluorescence methods can be utilized to assess enzymatic activity through the measurement of fluorescently labeled substrates or products, providing sensitive detection capabilities. Radiolabeling also allows for the tracking of substrates during an enzymatic reaction by using radioactive isotopes, thus quantifying the enzymatic activity based on the detection of radioactivity.

Each of these methods is specifically designed to quantify or analyze enzymatic reactions, distinguishing them clearly from electrophoresis, which is more suited for separation and identification rather than direct measurement of activity.