title: Multiple metal binding to 6-oxopurine nucleobases as a source of deprotonation. The role of metal ions at N7 and N3.
abstract: Simultaneous metal coordination to N7 (Pt(II)) and N3 (Pd(II)) of N9-blocked guanine leads to a 10(4) fold acidification of the guanine-N(1)H position and hence to a virtual complete deprotonation of the N(1)H position at neutral pH. The chelate-tethered nucleobase ethylenediamine-N9-ethylguanine was employed and relevant acid-base equilibria were studied by pD dependent 1H NMR spectroscopy. CH2 resonances of the tether were assigned on the basis of NOESY and COSY experiments. Our findings suggest a plausible method of formation of a previously reported trinuclear Pt(II) complex of 9-ethylguanine with metals coordinated to N1, N3 and N7. According to this, a sequence with the first metal binding to N7, the second one binding to N3, and only the third one binding to N1 with deprotonation of this site is proposed.
authors.affiliation: Fachbereich Chemie, Universität Dortmund, 44221, Dortmund, Germany.
authors.forename: Marta
authors.initials: M
authors.lastname: Morell Cerdà
authors.forename: David
authors.initials: D
authors.lastname: Amantia
authors.forename: Burkhard
authors.initials: B
authors.lastname: Costisella
authors.forename: Andrew
authors.initials: A
authors.lastname: Houlton
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lippert
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D006147:Guanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D006571:Heterocyclic Compounds; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011522:Protons; D011688:Purinones / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D009944:Organoplatinum Compounds; D011522:Protons; D011688:Purinones; D010984:Platinum; D010165:Palladium; D006147:Guanine; C014542:9-ethylguanine