Synthesis and degradation of nucleobases and nucleic acids by formamide in the presence of montmorillonites.
We describe the role of formamide, a product of the hydrolysis of hydrogen cyanide, as precursor of several components of nucleic acids under prebiotic conditions. When formamide is heated in the presence of montmorillonites, the efficient one-pot synthesis of purine, adenine, cytosine, and uracil is obtained. Along with these nucleobases, several components of the inosine pathway are obtained: 5-aminoimidazole-4-carboxamide, 5-formamidoimidazole-4-carboxamide and hypoxanthine. This almost complete catalogue of nucleic acid precursors is accompanied by N(9)-formylpurine, which, containing a masked glycosidic bond in its formyl moiety, is a plausible precursor of purine acyclonucleosides. In addition, montmorillonites differentially affect the rate of degradation of nucleobases when embedded in 2'-deoxyoligonucleotides; namely, montmorillonites protect adenine and guanine from the degradative action of formamide, while thymine degradation is enhanced. The oligonucleotide backbone reactivity to formamide is also affected; this shows that the interaction with montmorillonites modifies the rate of abstraction of the Halpha and Hbeta protons on the sugar moieties.
Saladino
Raffaele
R
Dipartimento A.B.A.C., Università della Tuscia, Via San Camillo De Lellis, 01100 Viterbo, Italy. saladino@unitus.it
Crestini
Claudia
C
Ciambecchini
Umberto
U
Ciciriello
Fabiana
F
Costanzo
Giovanna
G
Di Mauro
Ernesto
E
D001546:Bentonite / Q000737:chemistry*; D002384:Catalysis; D005559:Formamides / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009696:Nucleic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D011687:Purines / Q000138:chemical synthesis / Q000737:chemistry*; D011743:Pyrimidines / Q000138:chemical synthesis / Q000737:chemistry*
D005559:Formamides; D009696:Nucleic Acids; D009841:Oligonucleotides; D011687:Purines; D011743:Pyrimidines; D001546:Bentonite; C031066:formamide