REVIEW Alkylating agents work by three different mechanisms: 1) attachment of alkyl groups to DNA bases (primarily at the N-7 position of guanine and to a lesser extent, at the N-3 position of adenine), forming monoadducts and resulting in the DNA being fragmented by repair enzymes in their attempts to replace the alkylated bases, preventing DNA synthesis and RNA transcription from the affected DNA, 2) DNA damage via the formation of cross-links (bonds between atoms in the DNA) which prevents DNA from being separated for synthesis or transcription, and 3) the induction of mispairing of the nucleotides leading to mutations.
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Souliotis VL, Dimopoulos MA, Episkopou HG, Kyrtopoulos SA, Sfikakis PP: Preferential in vivo DNA repair of melphalan-induced damage in human genes is greatly affected by the local chromatin structure. DNA Repair (Amst). 2006 Aug 13;5(8):972-85. Epub 2006 Jun 15.
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