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5-Bromouracil (or 5-bromo-2,4(1H,3H)-pyrimidinedione or 5-BrU or 5-BU) is a brominated derivative of uracil that acts as an antimetabolite or base analog, substituting for thymine in DNA, and can induce DNA mutation in the same way as 2-aminopurine
A major chemical mutagen.