enzymemecatalyzed

Enzyme-catalyzed reactions are chemical transformations accelerated by biological catalysts known as enzymes. Most enzymes are proteins, though a class of RNA molecules called ribozymes also exhibits catalytic activity. Enzymes work by binding substrates at a specific region called the active site, forming an enzyme–substrate complex. The active site lowers the activation energy and stabilizes the transition state, allowing bonds to be formed or broken more readily than in uncatalyzed reactions.

Enzymes are typically highly specific, acting on particular substrates or groups of related substrates and catalyzing a single type of chemical transformation. Many enzymes require cofactors—such as metal ions or organic molecules (coenzymes)—to complete catalysis. Reaction rates depend on temperature, pH, substrate concentration, and enzyme concentration; extreme conditions can denature enzymes and reduce activity.

Regulation of enzyme activity is common in metabolism. Allosteric regulation and feedback inhibition enable cells to control pathways in response to internal and external signals. Inhibitors can affect enzymes competitively, by blocking substrate binding, or noncompetitively, by altering catalytic efficiency without blocking binding.

Examples of enzyme-catalyzed processes include digestion (amylase in saliva and pancreatic juice; proteases such as trypsin; lipases), lactose breakdown by lactase, and sucrose hydrolysis by sucrase. Enzyme-catalyzed reactions are characterized by high efficiency, specificity, and operation under mild cellular conditions, in contrast to many non-enzymatic reactions.

Note: the term “enzymemecatalyzed” is not standard; the conventional term is “enzyme-catalyzed” or “enzyme-mediated.”