Nucleic Acids Research, 1993, Vol. 21, No. 19 4499-4505
© 1993
CHEMISTRY |
Synthesis and hybridization properties of oligonucleotides containing 2'-O-modified ribonucleotides
Preclinical Research, Sandoz Pharma AG CH-4002 Basle, Switzerland
*To whom correspondence should be addressed
Received June 24, 1993. Revised August 17, 1993. Accepted August 17, 1993.
A versatile, general way is described for the introduction of different functional groups into oligonucleotides by means of a simple linker at the 2'-position of the sugar. Nucleotide building blocks carrying lipophilic, intercalating or tertiary amino groups can be placed deliberately at any desired position of oligonucleotides by standard automated oligonucleotide synthesis. Thermal denaturation studies with these oligonucleotides reveal the following general trends: i) Modification with lipophilic n-octyl groups has little if any effect on duplex stability; a destabilizing (lipophilic) substituent is better tolerated at or near the ends than in the middle of the oligo. ii) An intercalating substituent (2-aminoanthraquinone) substantially increases duplex stability, iii) N,NDimethyl amino residues also increase duplex stability though to a smaller extent than intercalating residues, iv) Modifications at the 5'-end have a more pronounced influence on the TMthan the corresponding 3'-modifications. v) Oligonucleotides modified in such a way show little or no loss in sequence specificity.