ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Solid-phase synthesis of the oligo(2′-deoxynucleotides) 19 and 20 containing 2′-deoxy-β-D-xylocytidine (4) is described. For this purpose, 1-(2-deoxy-β-D-threo-pentofuranosyl)cytosine ( = 1-(2-deoxy-β-D-xylofuranosyl)-cytosine; 4) was protected at its 4-NH2 group with a benzoyl (→ 5) or an isobutyryl (→8) residue, and a dimethoxytrityl group was introduced at 5′-OH (→ 7, 10; Scheme 2). Compounds 7 and 10 were converted into the 3′-phosphonates 11a,b. While 19 could be hybridized with 21 and 22 under formation of duplexes with a two-nucleotide overhang on both termini (19 · 21: Tm 29°; 19 · 22: Tm 22°), the decamer 20 bearing four xCd residues could no longer be hybridized with one of the opposite strands. Moreover, the oligonucleotides d[(xC)8—C] (13), d[(xC)4—C] (14), d[C—(xC)4—C] (15), and d[C—(xC)3—C] (16) were synthesized. While 13 exhibits an almost inverted CD spectrum compared to d(C9) (17), the other oligonucleotides show CD spectra typical for regular right-handed single helices. At pH 5, d[(xC)8—C] forms a stable hemi-protonated duplex which exhibits a Tm of 60° (d[(CH+)9] · d(C9): Tm 36°). The thermodynamic parameters of duplex formation of (13H+ · 13) and (17H+ · 17) were calculated from their melting profiles and were found to be identical in ΔH but differ in ΔS (13H+ · 13: ΔS = -287 cal/K mol; 17H+ · 17: ΔS = -172 cal/K mol).
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19940770402
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