Calicheamicin gamma 1I and DNA: molecular recognition process responsible for site-specificity.

ABSTRACT

Calicheamicin gamma 1I is a recently discovered diyne-ene-containing antitumor antibiotic that cleaves DNA in a double-stranded fashion, a rarity among drugs, at specific sequences. It is proposed that the cutting specificity is due to a combination of the complementarity of the diyne-ene portion of the aglycone with DNA secondary structures and stabilization by association of the thiobenzoate-carbohydrate tail with the minor groove.