How do enzymes work?
Enzymes are biological catalysts that accelerate biochemical reactions. Most are proteins, although some RNA molecules also catalyze reactions. They lower activation barriers without making the overall reaction more energetically favorable.
Active sites and specificity
Substrates bind at an active site, where structural fit and chemical interactions facilitate conversion. The lock-and-key analogy is limited because enzymes can change shape during binding. Temperature, pH, and cofactors influence activity. Increasing substrate can initially raise the rate, which later approaches a capacity limit as active sites become occupied. Higher temperature does not always mean greater activity.
Regulation and misconceptions
Cells regulate enzyme production and activity to control metabolic pathways. Inhibitors may compete at active sites or act elsewhere, and these mechanisms differ. Enzymes can be reused after catalysis but may become damaged and require replacement. Activity in a laboratory assay does not prove identical effects under every condition or inside an organism; environment and biological context remain important.