title: Polynucleotide helix geometry and stability. Spectroscopic, antigenic and interferon-inducing properties of deoxyribose-, ribose-, or 2'-deoxy-2'-fluororibose-containing duplexes of poly(inosinic acid) . poly(cytidylic acid).
abstract: Circular dichroism, absorbance temperature profiles, antigenic properties, and interferon-inducing capacity of the nine double-stranded complexes between poly(inosinic acid) and poly(cytidylic acid) [(rI)n . (rC)n] and their deoxy- and 2'-deoxy-2'-fluoro-analogues were studied. The complexes containing only ribose or 2'-fluororibose chains showed similar CD spectra and thermal stabilities. Anti-(rI)n . (rC)n antibodies were well recognized by the duplexes containing 2'-fluororibose in either one strand. These two duplexes were also efficient interferon inducers. Presence of fluororibose in both strands decreased the affinity of anti-(rI)n . (rC)n antibodies slightly and abolished interferon-inducing activity. All polydeoxyriboside-containing complexes showed CD spectra significantly different from the previous group; they showed also 40- to 100-times lower affinity for the anti-(rI)n . (rC)n antibodies, and did not induce interferon. It is concluded that the structure of (rI)n . (rC)n, an A-type helix, is little perturbed by substitution of one or both strands by 2'-fluororibose. Substitution by deoxyribose in either strand considerably changes the structure of the helices. The hybrids containing poly(deoxycytidylic acid) retain at least some of the structural features of the B-type helix poly(deoxyinosinic acid) . poly(deoxycytidylic acid).
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002942:Circular Dichroism; D003855:Deoxyribose / Q000031:analogs & derivatives*; D000939:Epitopes / Q000032:analysis; D005779:Immunodiffusion; D007372:Interferons / Q000096:biosynthesis; D007668:Kidney / Q000187:drug effects; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011069:Poly I / Q000276:immunology / Q000494:pharmacology; D011070:Poly I-C / Q000276:immunology / Q000494:pharmacology; D011817:Rabbits; D011863:Radioimmunoassay; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D000939:Epitopes; D011069:Poly I; D003855:Deoxyribose; C033285:2'-deoxy-2'-fluororibose; D007372:Interferons; D011070:Poly I-C