What is the Difference Between Enzyme Activity and Specific Activity?

The difference between enzyme activity and specific activity lies in their definitions and how they are measured.

• Enzyme activity refers to the number of substrates transformed into products per unit time by an enzyme. It is a measure of the quantity of active enzyme present and is dependent on the conditions under which the enzyme is tested.
• Specific activity is the activity of an enzyme per milligram of total protein (expressed in μmol min−1 mg−1). It is a measure of enzyme processivity (the capability of an enzyme to be processed) at a specific, usually saturating, substrate concentration. Specific activity gives a measurement of enzyme purity in a mixture and is calculated by dividing the number of units/mL by the protein concentration in mg/mL.

In summary, enzyme activity measures the ability of an enzyme to catalyze a specific reaction, while specific activity measures the enzyme's activity per milligram of protein. Specific activity is a more accurate indicator of enzyme purity and processivity than enzyme activity alone.

Comparative Table: Enzyme Activity vs Specific Activity

Enzyme activity and specific activity are both measures related to the effectiveness of enzymes in catalyzing reactions. However, they differ in their focus and application. Here is a table highlighting the differences between enzyme activity and specific activity:

In summary, enzyme activity measures the overall catalytic activity of an enzyme solution, while specific activity provides a more focused measure of the activity of the target protein. Specific activity is useful for evaluating protein purity and the yield of purification processes, whereas enzyme activity is used to compare different enzyme preparations and assess their efficiency.