Antimetabolite
An antimetabolite is a substance that resembles or disrupts a metabolite, interfering with its production or use in biological processes.
Competitive inhibition: A form of enzyme inhibition in which a molecule competes with the substrate for the enzyme’s active site. Many antimetabolites resemble natural substrates and compete for the same enzyme binding sites.
Methotrexate: A drug that inhibits dihydrofolate reductase and is used to treat cancers, autoimmune diseases, and other conditions. It blocks folate recycling, limiting nucleotide synthesis and rapidly dividing cell growth.
Metabolite: A small molecule produced, used, or transformed by metabolism. Antimetabolites interfere with the normal production or use of these molecules.
Alkylating agent: A reactive chemical that adds alkyl groups to DNA or other molecules, often damaging DNA and disrupting replication. Unlike antimetabolites, alkylating agents typically damage DNA directly rather than mimic metabolites.
Substrate analogue: A molecule resembling an enzyme’s natural substrate that can bind to the enzyme and alter its activity. Structural resemblance lets an antimetabolite enter reactions intended for a normal metabolite.
5-Fluorouracil: A fluorinated pyrimidine drug used mainly in cancer treatment that disrupts thymidylate production and RNA function. It is a classic anticancer antimetabolite that impairs DNA synthesis.
Enzyme: A biological catalyst that accelerates a chemical reaction without being consumed. Enzymes are frequent targets when antimetabolites block a metabolic reaction.
Mitotic inhibitor: A drug that disrupts cell division by interfering with mitotic structures or processes. These drugs target cell division machinery, not the metabolic pathways antimetabolites imitate or block.
Enzyme inhibition: A reduction in an enzyme’s activity caused by a molecule binding to it or otherwise disrupting its function. Blocking metabolic enzymes is one of the main ways antimetabolites interfere with cell processes.
Cytarabine: A cytidine analogue used in chemotherapy, especially for acute myeloid leukemia, that interferes with DNA synthesis. Its incorporation into DNA helps explain how nucleotide-like antimetabolites halt cancer-cell replication.