Optimizing the stacking moiety and linker of 2'-acylamido caps of DNA duplexes with 3'-terminal adenine residues.
Reported here is the synthesis of oligodeoxynucleotides with a 3'-terminal 2'-acylamido-2'-deoxyadenosine residue. The route to these oligonucleotides employs an N,O-Alloc-protected 5'-phosphoramidite of 2'-amino-2'-deoxyadenosine that was prepared in 11 steps from arabinoadenosine. Small combinatorial libraries of oligonucleotides were generated via acylation with a mixture of linker amino acids and subsequent acylation of their amino groups. Mass spectrometrically monitored nuclease selection assays led to oligonucleotides whose 2'-substituent increases the thermal stability of the DNA duplexes. A linker with three methylene groups between a perylene stacking moiety and the amido group gives a UV-melting point increase of up to 27.9 degrees C for the DNA sequence (TGCGCA*)2, where A* denotes the 2'-acylamidoadenosine residue. The same acylamido group improves mismatch discrimination at the terminal position with a melting point depression of >or=7 degrees C for any of the three mismatches in the target sequence of the octamer 5'-AGGTTGAA-3'. These results demonstrate how even a very weakly base-pairing nucleotide at the 3'-terminus of a DNA probe strand can be enforced to engage in strong and highly sequence-selective base-pairing interactions.
Printz
Michael
M
Institute for Organic Chemistry, University of Karlsruhe (TH), 76131 Karlsruhe, Germany.
Richert
Clemens
C
D000225:Adenine / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D016339:Spectrometry, Mass, Fast Atom Bombardment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000577:Amides; D004247:DNA; D000225:Adenine