Multiple metal binding to 6-oxopurine nucleobases as a source of deprotonation. The role of metal ions at N7 and N3.
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.
Morell Cerdà
Marta
M
Fachbereich Chemie, Universität Dortmund, 44221, Dortmund, Germany.
Amantia
David
D
Costisella
Burkhard
B
Houlton
Andrew
A
Lippert
Bernhard
B
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*
D006571:Heterocyclic Compounds; D009944:Organoplatinum Compounds; D011522:Protons; D011688:Purinones; D010984:Platinum; D010165:Palladium; D006147:Guanine; C014542:9-ethylguanine