Triple-stranded polynucleotide complexe

The existence of conformational determinants has been clearly demonstrated through the use of synthetic polynucleotides in double-hehcal structures and in triple-stranded complexes. It has also been shown that the specificity of antibodies is determined by the macromolecular conformation of the immunogen. Thus single-stranded polynucleotides induce formation of antibodies specific for the single-strand, while double-stranded hehcal complexes of polynucleotides induce antibodies specific for these structures, and antibodies specific for triple-strand structures are induced by the triple-stranded polynucleotide complexes. 

In order to elucidate the role of conformation of the immunogen, animals were immunized with complexes of polyribonucleotides (double- or triple-stranded) associated with MBS A. The antibodies obtained reacted specifically with double- or triple-stranded complexes and it was concluded that the specificity was determined by the macromolecular conformation of the immunogen (Nahon et al., 1967 Lacour et al., 1968 Michelson et al., 1971). Immunization of rabbits with DNA-MBSA or with double-stranded polynucleotide complexes adsorbed to MBS A ehcits antibodies belonging to the macroglobulin class (Stollar and Sandberg, 1966 Nahon-Merlin et al., 1973). 

Recently, Sakurai et al. reported the first example of i8-l,3-glucan forming a macromolecular complex with some polynucleotides that is, when the renaturing of )8-l,3-glucan was carried out in the presence of some polynucleotides, it formed novel triple-stranded structures consisting of two 8-1,3-... 

Anti-poly G poly C antibodies have been demonstrated by immunodiffusion and by complement fixation in the sera of rabbits immunized with poly G-poly C — MBSA (Michelson et al., 1971 Nahon-Merlin et al., 1971). The anti-poly G poly C antibodies react not only with poly G poly C but also with a large number of double-helical complexes such as poly A poly U, poly I poly C and poly dG poly dC. It is nevertheless to be noted that the complex poly A poly I in which two purine polynucleotides are involved is not precipitated by these antibodies, which is readily explained by the special stereochemical structure of this complex. The anti-poly G poly C antisera nevertheless precipitate poly iso A poly I, but in this case it can be considered that displacement of the glycosyl-hnkage from N to in polyisoadenylic acid converts this polynucleotide into an analogue of poly C. The complex is thus effectively between a poly purine ribonucleotide and a poly pyrimidine ribonucleotide as in the case of other complexes such as poly A poly U and poly I poly C. Immune sera against poly G poly C also react with the triple-stranded complex 2 poly G poly C. In addition they can precipitate one or the other of the component polynucleotides of the homologous complex. 

Abbreviations DNA deoxyribonucleic acid RNA ribonucleic acid rRNA ribosomal RNA tRNA transfer RNA. A adenine U uracil G guanine C cytosine, poly A polyadenylic acid poly U polyuridylic acid poly C polycytidylic acid poly I poly-inosinic acid poly G polyguanylic acid. The letters r and d refer to the ribose or deoxy-ribose series. Complexes between the polynucleotides are written as follows polyG poly C double-stranded helical complex of poly G and poly C 2 poly G poly C, triple-stranded complex. BSA bovine serum albumin MBSA methylated bovine serum albumin. N nitrogen. AMV Avian myeloblastosis virus NDV Newcastle disease virus. SLE systemic lupus erythematosus. 

Table 5 (section 3.2.2.4) contains melting temperatures of complexes between the same polynucleotide (homo-complexes). This table contains double, triple and four stranded complexes. Also included ate several polynucleotides which have no structure which is indicated as that... 

In order to give DNA immunizing properties Plescia et al. (1964, 1965) complexed the material to MBS A. A certain number of polynucleotides such as denatured DNA, poly dAT, and tRNA associated with MBS A have been used as immunogens by these authors. This method of preparation has been used for other polynucleotides, particularly for single-stranded synthetic polynucleotides and the various double- and triple-hehcal complexes formed from such polyribonucleotides. It appears that secondary structure of these complexes is generally maintained on adsorption onto MBS A, although some of their characteristics could well be modified in this electrostatic interaction. 

Another y9-(1 3)-D-glucan, named schizophyllan as an antitumor polysaccharide, has been obtained from Schizophylium commune [8,9]. Schizophyllan has similar chemical structure and triple-helix as lentinan [17], as shown in Figure 4. Since Sakurai and Shinkai were the first to find that schizophyllan may form a helical complex with single-stranded homo-polynucleotides [18], many works about preparing a complex of schizophyllan and... 

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