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Coordination and Noncovalent Interactions in the Systems of Copper(II), Guanosine and Biogenic Amine

Jastrząb R., Lomozik L.

Polish Journal of Chemistry

2007

Vol. 81, nr 7

1289-1302

Molecular complex formation between guanosine (Guo) and biogenic amines: putrescine (Put), spermidine (Spd) and spermine (Spm) as well as coordination of these ligands with the copper(II) ions have been studied. It has been found that the positive centres of noncovalent ion-dipole interactions are the protonated amine groups of the polyamines, while the negative centres are the endocyclic nitrogen atoms N(7) or N(1) of guanosine. In the binary systems at low pH, the main site of noncovalent interaction and a metallation centre in guanosine is the nitrogen atom N(7). With deprotonation of N(1), the reaction centre shifts from N(7) to N(1). At high pH the nitrogen atom N(1) becomes the main centre of interactions between the nucleoside and polyamines (PA) and it also becomes an effective site of Cu(II) ions bonding. The addition of spermine to the Cu(II)/guanosine system leads to a disappearance of the coordination dichotomy observed in binary systems, whereas the introduction of putrescine and spermidine extends the range of the dichotomy to high pH values.

Purine nucleoside analogues. 8. N(2) - acetylation of guanine derivatives

Madre M., Zhuk R., Golankiewicz B.

Polish Journal of Chemistry

1998

Vol. 72, nr 10

2242-2246

A method for the acetylation of the exocyclic amino group of guanine derivatives has been developed. A series of N(2)-acetylguanines was synthesized by reacting of N-9(7)-alkoxyalkylguanines with an excess of acetic anhydride in the presence of 4-dimethylaminopyridine. The method has been used successfully also for N(2)-acetylation of guanosine and its 8-bromo derivative although in the latter case a partial substitution of bromine for a hydroxy group at the position 8 of the heterocycle occurred.