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|Section2= |Section3= |Section4= |Section5= |Section6= |Section7= |Section8= }} The calicheamicins are a class of enediyne antitumor antibiotics derived from the bacterium ''Micromonospora echinospora'', with calicheamicin γ1 being the most notable. It was isolated originally in the mid-1980s from the chalky soil, or "calichi pits", located in Kerrville, Texas. The sample was collected by a scientist working for Lederle Labs.〔 (Total Synthesis and the Creative Process: An Interview with K.C. Nicolaou ), Scripps Research Institute〕 It is extremely toxic to all cells and, in the year 2000, a CD33 antigen-targeted immunoconjugate N-acetyl dimethyl hydrazide calicheamicin was developed and marketed as targeted therapy against the non-solid tumor cancer acute myeloid leukemia (AML). Calicheamicin γ1 and the related enediyne esperamicin are the two of the most potent antitumor agents known.〔(Calicheamicin and Esperamicin are the two most potent antitumor agents known to man ), Univ Of Georgia, Chem 4500〕 ==Mechanism of toxicity== Calicheamicins target DNA and cause strand scission. Calicheamicins bind with DNA in the minor groove, wherein they then undergo a reaction analogous to the Bergman cyclization to generate a diradical species. This diradical, 1,4-didehydrobenzene, then abstracts hydrogen atoms from the deoxyribose (sugar) backbone of DNA, which ultimately leads to strand scission. The specificity of binding of calicheamicin to the minor groove of DNA was demonstrated by Crothers et al. (1999) to be due to the aryltetrasaccharide group of the molecule. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「calicheamicin」の詳細全文を読む スポンサード リンク
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