enzyme saturation

Enzyme saturation occurs when all the active sites of enzymes—proteins that speed up chemical reactions—are occupied by molecules called substrates. At low substrate levels, enzymes work efficiently, quickly converting substrates into products. However, as substrate concentration increases, more active sites are occupied until no more can bind at once. When this happens, adding more substrate doesn’t increase the reaction rate because the enzymes are "busy." This point is called enzyme saturation, and it represents the maximum rate at which the enzyme can catalyze the reaction under those conditions.