Enzyme assay

An experimental procedure that measures enzyme activity by tracking substrate consumption or product formation. Its result depends on defined conditions such as temperature, pH, and substrate concentration.

Initial rate: The reaction rate measured near the start, before substrate depletion or product buildup substantially changes the reaction. Initial-rate measurements best isolate activity before changing reaction conditions distort the result.
Enzyme: A biological catalyst that accelerates chemical reactions without being consumed overall. The assay measures the catalytic activity of this molecule.
High-throughput screening: Automated testing of many samples or compounds in parallel using miniaturized assays. Enzyme assays provide measurable signals for screening large compound libraries.
Endpoint assay: An assay that measures reaction progress at one selected time rather than continuously. It contrasts with continuous monitoring of reaction rates throughout the assay.
Michaelis–Menten kinetics: A model relating enzyme reaction rate to substrate concentration for a simple enzyme-catalyzed reaction. Varying substrate concentration lets an assay estimate kinetic parameters from measured rates.
Substrate: A molecule on which an enzyme acts to produce one or more products. Its consumption or conversion supplies the reaction being measured.
Drug discovery: The process of identifying and developing compounds that can become therapeutic drugs. Assays identify compounds that inhibit or otherwise alter target enzyme activity.
Continuous assay: An assay that monitors a reaction signal repeatedly or continuously as the reaction proceeds. Its time-resolved signal can reveal rate changes hidden by a single endpoint.
Spectrophotometry: A method that measures how much light a sample absorbs or transmits at selected wavelengths. Absorbance changes can track substrate disappearance or product formation over time.
Enzyme kinetics: The study of how enzyme reaction rates depend on conditions such as substrate concentration and inhibitors. Kinetic principles explain how assay conditions shape observed activity.

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