title: Covalent Bonding of Pyrrolobenzodiazepines (PBDs) to Terminal Guanine Residues within Duplex and Hairpin DNA Fragments.
abstract: Pyrrolobenzodiazepines (PBDs) are covalent-binding DNA-interactive agents with growing importance as payloads in Antibody Drug Conjugates (ADCs). Until now, PBDs were thought to covalently bond to C2-NH2 groups of guanines in the DNA-minor groove across a three-base-pair recognition sequence. Using HPLC/MS methodology with designed hairpin and duplex oligonucleotides, we have now demonstrated that the PBD Dimer SJG-136 and the C8-conjugated PBD Monomer GWL-78 can covalently bond to a terminal guanine of DNA, with the PBD skeleton spanning only two base pairs. Control experiments with the non-C8-conjugated anthramycin along with molecular dynamics simulations suggest that the C8-substituent of a PBD Monomer, or one-half of a PBD Dimer, may provide stability for the adduct. This observation highlights the importance of PBD C8-substituents, and also suggests that PBDs may bind to terminal guanines within stretches of DNA in cells, thus representing a potentially novel mechanism of action at the end of DNA strand breaks.
authors.affiliation: Institute of Pharmaceutical Science, King's College London, 7 Trinity Street, London, SE1 1DB, United Kingdom.
authors.forename: Julia
authors.initials: J
authors.lastname: Mantaj
authors.affiliation: Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom.
authors.forename: Paul J M
authors.initials: PJ
authors.lastname: Jackson
authors.affiliation: UCL Chemistry Mass Spectrometry Facility, Christopher Ingold Building, Chemistry Department, 20 Gordon Street, London, WC1H 0AJ, United Kingdom.
authors.forename: Kersti
authors.initials: K
authors.lastname: Karu
authors.affiliation: Institute of Pharmaceutical Science, King's College London, 7 Trinity Street, London, SE1 1DB, United Kingdom.|Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom.
authors.forename: Khondaker M
authors.initials: KM
authors.lastname: Rahman
authors.affiliation: Institute of Pharmaceutical Science, King's College London, 7 Trinity Street, London, SE1 1DB, United Kingdom.|Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom.
authors.forename: David E
authors.initials: DE
authors.lastname: Thurston
mesh_terms: D000876:Anthramycin / Q000737:chemistry; D001569:Benzodiazepines / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D053960:DNA Breaks; D006147:Guanine / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D009690:Nucleic Acid Conformation; D011758:Pyrroles / Q000737:chemistry*
chemical_list: D011758:Pyrroles; C438462:pyrrolo(2,1-c)(1,4)benzodiazepine; D000876:Anthramycin; D001569:Benzodiazepines; D006147:Guanine; D004247:DNA