The reactivity of phosphodiester bonds within linear single-stranded oligoribonucleotides is strongly dependent on the base sequence.
The cleavage of short chimeric oligonucleotides containing only one reactive ribonucleoside unit, all other nucleosides being 2'-O-methylated, has been studied at pH 8.5 and 35 degrees C. Among the 20 different sequences that did not exhibit any tendency to form a defined secondary structure, the scissile 5'-UpA-3' and 5'-CpA-3' phosphodiester bonds experienced >100- and up to 35-fold reactivity differences, respectively. Compared with dinucleoside monophosphates, both rate accelerations and retardations of more than one order of magnitude were observed. Even a change of a single base several nucleosides away from the scissile bond markedly affected the reaction rate. Duplex formation at the 3'- and/or 5'-side of the scissile bond was also studied and observed to be strongly rate retarding. The origin of the high sensitivity of phosphodiester bonds to the molecular environment is discussed.
Kaukinen
Ulla
U
Department of Chemistry, University of Turku, Vatselankatu 2, FIN-20014 Turku, Finland.
Lyytikäinen
Sari
S
Mikkola
Satu
S
Lönnberg
Harri
H
D001482:Base Composition; D001483:Base Sequence; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009843:Oligoribonucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013696:Temperature
D009843:Oligoribonucleotides