PHENYLALKYL BACKBONE MODIFIED OLIGODEOXYNUCLEOTIDES, THEIR SYNTHESIS AND THE INFLUENCE OF THE ALKYL CHAIN LENGTH
摘要:
Phenylalkyl modified phosphoramidites (alkyl chain length n = 1, 2, 3, 5; Fig. 1) were synthesised and incorporated into a DNA hexamer (5'-d(GCCp-GCG); p = place of modification). The obtained diastereomeres were separated by RP-HPLC. After hybridisation with the complementary DNA strand T-m-value and thermodynamic data were measured. The stability of duplexes depends on the linker length and the absolute configuration of the backbone modified oligodeoxynucleotides (Rp, Sp).
Synthesis and Properties of Nonpolar DNA (Arylalkyl)phosphonates
摘要:
The eight (arylalkyl)-modified phosphoramidites (=(arylalkyl)phosphonamidites) 1-8 (Fig. 2) were synthesized (Schemes 1-3) and incorporated at different positions into 2'-deoxyoligonucleotides. The [P(R)]and [P(S)]-diastereoisomers of the hexanucleotides 32-39 (Table 1) and of the dodecanucleotides 41-45 (Table 2) obtained were separated by means of reversed-phase HPLC. UV, CD, and fluorescence spectroscopy were used to investigate the thermal stability (T-m) and the structural changes of their DNA duplexes with 5'-d(CGCGCG)-3' and 5'-d(ATGATTGACCTG)-3', respectively. The T-m values significantly depend on the place of modification (Table 2). A dangling-end effect is observed when the [3-(anthracen-9-yl)propyl]-modified 8 is attached at the 5'-terminus (see duplex with 45c). In the case of the incorporation of aromatic moieties tethered via a methylene linker to the P-atom (benzyl- and (naphthalen-1-ylmethyl)-modified 1 and 6, resp.), the duplexes with the [P(R)]-oligonucleotides are more stable than those with the [P(S)]-isomers, whereas in the case of longer alkyl chains at the P-atom (see 2-5), the T-m values show the reverse tendency. The observed T-m differences are assigned to changes in base stacking (Figs. 6 and 7).