Immunochimie des polyribonucléotides

Immunochemistry of polyribonucleotides. Study of polyriboinosinic and polyriboguanylic acids

“…The results are similar with poly G, but the four-stranded structure is stable in a 4 X 10"4 m Mg2+ solution (Figure 3). Figure 4 shows that a gradual decrease in the amount of antibody precipitated parallels the precipitation of multistranded molecules of poly I or poly G, reflecting the masking of antigenic sites that we have shown to be a general character of ordered molecules of polyribonucleotides in singleor multistranded conformation (Panijel et al, 1966b;Souleil et al, 1966). The masking of antigenic sites results in a 20% decrease in the maximum amount of antibody precipitable by poly I or poly G as compared with poly U.…”

“…The NG I antibodies were prepared from the euglobulins of sera obtained by hyperimmunization of a horse with 70S ribosomes of Proteus vulgaris Boulgakov. The preparation and purification of these antibodies have been described (Panijel et al, 1966b). Briefly, they are isolated by specific precipitation with poly A, dissociated in 1 m MgCl2, chromatographed on Sephadex G 200 in 0.5 m MgCl, and dialyzed successively against 0.15 M NaCl-0.0015 m Tris-HCl (pH 7.4), EDTA (0.002 m), and three-times-distilled water or 0.0015 m Tris (pH 7.1).…”

“…An increase in the amount of nucleotides precipitable was observed similarly under conditions which favor interaction of strands: with poly A at acid pH and with a mixture of poly U and adenylic acid (J. Panijel, unpublished data). On the contrary, this increase of antigen precipitable has never been observed with ordered single-stranded molecules, like poly A or poly C near neutrality (Panijel et al, 1966b). In this report, we have used this particular aspect of the reaction between NG I antibodies and polyribonucleotides as a tool for the determination of the number of strands of poly I and poly G in solution, under various conditions.…”