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At least 19 recordsLinked to original sources
PubMed1978

Specificity and crossreactivity of idiotypes of murine antibodies induced by poly(Tyr,Glu)-poly(DLAla)-poly(Lys) and poly(Phe,Glu)-poly(DLAla)-poly(Lys).

Antibodies elicited against the two synthetic polypeptides, poly(Tyr,Glu)-poly(DLAla)-poly(Lys) [(T,G)-A-L] and poly(Phe,Glu)-poly(DLAla)-poly(Lys) [(Phe,G)-A-L], are crossreactive although the humoral responses to these immunogens are under different genetic controls. The fine specificity of the antibodies elicited by the two polypeptides was studied in the present work. Antisera against (Phe,G)-A-L bind both (125)I-labeled (T,G)-A-L and iodinated modified (Phe,G)-A-L. However, while the binding to (T,G)-A-L could be inhibited completely with the two antigens, the binding to (Phe,G)-A-L was inhibited completely with (Phe,G)-A-L and only partially with (T,G)-A-L. The binding of (125)I-labeled (T,G)-A-L to antisera against (T,G)-A-L was inhibted more efficiently by the homologous antigen than by (Phe,G)-A-L although both antigens completely inhibited the binding. (T,G)-A-L specific antibodies were purified on (T,G)-A-L immunoadsorbents from antisera of high and low responder mice to (T,G)-A-L immunized with (Phe,G)-A-L. (Phe,G)-A-L specific antibodies that did not bind (T,G)-A-L were isolated from the effluent of these columns. By use of anti-idiotypic antibodies of guinea pig against C3H.SW antibodies to (T,G)-A-L it was shown that (T,G)-A-L specific antibodies isolated from antisera against (Phe,G)-A-L of C3H.SW and C3H/DiSn mice possess part of the idiotypic determinants existing on antibodies of C3H.SW obtained by immunization with (T,G)-A-L. In contrast, antibodies to (Phe,G)-A-L that did not bind (T,G)-A-L did not share idiotypic determinants with C3H.SW antibody molecules against (T,G)-A-L. These results suggest that the B cell repertoire expressed by high and low responders to (T,G)-A-L after immunization with (Phe,G)-A-L is similar and represents only part of that of high responders immunized with (T,G)-A-L.

Animals↗
PubMed1978

Poly(dG).poly(dC) at neutral and alkaline pH: the formation of triple stranded poly(dG).poly(dG).poly(dC).

Alkaline titrations of different samples of poly(dG).poly(dC) and of the constituent homopolymers poly(dG) and poly(dC) have been performed in 0.15 M NaCl and their CD spectra followed. Sample I contained a slight excess of poly(dC) (52% C: 48% G) and showed a single reversible transition (pK = 11.9) due to the dissociation of double stranded poly(dG).poly(dC). Sample II, containing an excess of poly(dG) (43% C: 57% G), showed two transitions (pK1 = 11.4, PK2 = 11.9) the first one being only partially reversible. Examination of the CD spectra along the alkaline titrations indicated the presence of another hydrogen-bonded complex of higher G content. Mixing curves performed at pH 8 have confirmed the presence of a 2G: 1C complex, besides the double stranded complex. It can be formed in amounts up to 30% by mixing the two homopolymers, alkali treatment and heating. The CD spectra of the two complexes have been computed from the CD data of the mixing curves. This permitted the determination of the concentrations of both complexes and homopolymers in all samples. The ratio of triple to double stranded complex is not only dependent on the G/C ratio of the sample, but also a function of the previous physico-chemical conditions. These results explain the variability of many properties of different poly(dG).poly(dC) samples observed by other workers.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Metal complexes of poly(alpha-amino acids). A potentiometric and circular dichroism investigation of Cu(II) complexes of poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid).

The conformational properties of cupric complexes of poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid) have been investigated by potentiometric, visible and UV absorption, and circular dichroism (CD) techniques. The three polymers form two kinds of complexes stable at pH less than 8.5 (type I complexes) and at pH less than 8.5 (type II complexes). It has been found that in the low pH complexes of poly(L-diaminobutyric acid) at least one deprotonated amido nitrogen is coordinated to cupric ions. Type II complexes involve always amide nitrogens in the coordination sphere of Cu(II). Evidence is presented that the structure of such complexes is not compatible with the alpha-helical conformation of the peptide backbone.

Aminobutyrates↗
PubMed1977

Antisera to poly(A)-poly(U)-poly(I) contain antibody subpopulations specific for different aspects of the triple helix.

Rabbit antibodies to the triple-helical polynucleotide poly(A)-poly(U)-poly(I) were fractionated into three major antibody populations, each recognizing a different conformational feature of the triple-helical immunogen. Two distinct populations were purified from precipitates made with poly(A)-poly(U)-poly(U) and poly(A)-poly(I)-poly(I). The former reacted with double-stranded poly(A)-poly(U) or poly(I)-poly(C), and similar populations could be purified with either double-stranded form. The second population recognized the poly(A)-poly(I) region of the triple helix, and the third required all three strands for reactivity. These immunochemical studies suggest that the poly(A) and poly(U) have the same orientation in the triple-helicical poly(A)-poly(U)-poly(I) as in the double-helical poly(A)-poly(U), in which they have Watson-Crick base pairing.

Animals↗
PubMed1975

Immunochemical characterization of the anti-RNA antibodies found in scleroderma and systemic lupus erythematosus. I. Differences in reactivity with Poly (U) and Poly-(A) Poly (U).

In a previous study, all 40 sera from patients with scleroderma, 20 of 40 sera from SLE patients, but none of 40 sera from normal controls, were found to have antibodies to ssRNA. All scleroderma sera were also found to react with HSA-coupled uridine and UMP and their reaction with HSA-coupled uridine and UMP and their reaction with ssRNA could be inhibited by uracil, uridine, and UMP. To characterize further these uracil-specific anti-RNA antibodies found in scleroderma and compare them with the anti-RNA antibodies found in SLE, we tested their reactivity with Poly (U) and with Poly (A)-Poly (U) and all but one failed to react with Poly (A)-Poly (U). This same serum was the only one in which the reaction with Poly (U) could not be inhibited with uracil. Reactivity of SLE sera was strikingly different from that found in scleroderma sera. Seventeen of 34 SLE sera studied reacted with ssRNA but only four of these reacted with Poly (U). Conversely, two SLE sera that reacted with Poly (U) did not react with ssRNA. Fifteen reacted with Poly (A)-Poly (U) and only two of these failed to react with ssRNA. Five SLE sera which were reactive with ssRNA did not precipitate with Poly (A)-Poly (U). All SLE sera which reacted with Poly (U) could be inhibited with uracil, although less effectively than in scleroderma. Reactivity with Poly (A)-Poly )U) was not inhibited with uracil nor with adenosine. These findings confirm that antibodies to RNA that are found in scleroderma are directed to uracil and thus specific to ssRNA, whereas RNA antibodies found in SLE sera are heterogeneous and directed to either the base, to the site of union of the base and sugar moiety to the ribose backbone, or to the helical structure of double stranded RNA. These differences and the respective antigenic specificities of these anti-RNA antibodies found in scleroderma and SLE may be theoretically important.

Adenine↗
PubMedDate not supplied

[Reaction capabilities and structure of poly(rG) and poly(rG)-poly(rC) in solution by the method of the kinetics of hydrogen ion exchange].

Data on the kinetics of 1H greater than 3H exchange between water and C(8)H groups of guanylic residues in the poly(rG) and poly poly(rG)-poly(rC) are presented. Furthermore, optical properties (CD spectra and hyperchromism) of neutral solutions of these polymers from 20 to 100 degrees C are described. It is shown that the exchange in poly(rG) within the temperature range from 20 to 80 degrees C proceeds faster than in rGMP. Within the temperature range from 20 to 40 degrees C such an acceleration of the exchange is observed also in poly(rG)-poly(rC). According to the ylide mechanism of the exchange reaction the observed accleration of the exchanged in in C(8)H groups of guanylic residues is considered as a consequence of an increase of the positive charge at N(7) atoms. This effect is due to formation of additional hydrogen bonds in which N(7) atoms take part. The exchange in poly(rG)-poly(rG) at temperatures hihger than 75 degrees C, when these additional hydrogen bonds are absent, proceeds more slowly than in rGMP. Such picture is usual in other previously studied polynucleotides whose structure in solution is stabilized only by Watson - Crick hydrogen bonds and stacking interactions. The data obtained support a Guschelbauer's model of the four-stranded stranded poly(rG). They also indicate the posibility of associates formation in poly(rG)-poly(rC) solutions at temperature lower than 40 degrees C being stabilized by hydrogen bonds in which N(7) atoms of guanylic residues take part.

Chemical Phenomena↗
PubMedDate not supplied

[Influence of a complex of poly(I). poly(C) and poly-l-lysine on the course of vaccinia in monkeys].

Experiments of 22 Macaca rhesus monkeys were carried out to study the interferon-inducing and antiviral activity of poly(I) - poly(C) and of its complex with poly-l-lysine. The complexed double-stranded polyribonucleotide induced active production of serum interferon and markedly protected the monkeys inoculated intradermally with vaccinia virus (10 monkey ID50 by intradermal inoculation). The effectiveness of the protective effect depended on the schedule and routes of administration of the preparation. The greatest prophylactic and therapeutic effect was achieved by local administration of the complex in a dose of 1 mg/1 kg of body weight. This also prolonged the incubation period by 2-3 times and reduced the duration of persistence of skin lesions approximately by half. By the intravenous route, the best protection was achieved by 2 injections of 2 mg/kg at an interval of 96 hours. Four daily injections of the complex exerted virtually no effect on the course of vaccinia infection. The animals receiving the complexed poly(I) - poly(C) developed virus-neutralizing antibody to the same titres as control animals and were resistant to reinfection with vaccinia virus. A second injection of the complexed poly(I)-poly(C) 96 hours after the primary inoculation induced the same interferon production as the initial administration of the preparation. The monkeys inoculated intravenously with 2 mg/kg poly(I) - poly(C) showed no interferon in their blood serum and were also poorly protected against vaccinia virus infection.

Animals↗
PubMed1976

Protonated polynucleotide structures, 20. Interaction between poly(dG)-poly(dC) and poly(rC).1.

A study of the interaction between poly(dG)-poly(dC) and poly(rC) demonstrates that, at neutral pH and high ionic strength, there is replacement of the dC strand by poly(rC). At acid pH, formation of a triple-stranded complex which equally may involve the replacement phenomenon is observed. There is no evidence for interaction at neutral pH between poly(dG)-poly(dC) and oligo(rC), while a three-stranded complex is formed at acid pH. These data are consistent with the studies of comparative stabilities of double stranded deoxy or ribo polymers and deoxy-ribo hybrids.

Circular Dichroism↗
PubMed1977

[Study of the antiviral activity of a poly I : poly-C complex with poly-L-lysine in monkeys].

Antiviral activity of poly-I-poly-C complex with poly-L-lysine was studied on macaco rhesus. The complex bifilamentous polyribonucleotide induced active production of serum interferon and provided pronounced protection of the monkeys infected intracutaneously with the variolovaccine virus (10 LD50 for the monkeys in intracutaneous infection). The effectiveness of the protective effect depended on the scheme and route of the drug administration. The highest prophylactic and therapeutic effect was provided by local administration of the complex in a dose of I mg per I kg of the body weight, the incubation period being increased 2--3 times and the period of the skin affections being decreased approximately 2 times. The results of the studies on the effect of poly-I-poly-C complex with poly-L-lysine were evident of definite prophylactic activity of the drug against experimental vernal encephalitis in the monkeys. The animals not treated with the inductor died on the 16th or 17th day after infection because of the paralysis of the trunc and extremities muscles. The clinical evidences of the disease in the animals treated with the drug were not uniform: from complete health to death.

Animals↗
PubMedDate not supplied

[Effect of a poly I-poly C complex with poly-L-lysine on experimental tick-borne encephalitis].

The influence of the poly(I)-poly(C) complex with poly-l-lysine on the development and course of experimental tick-borne encephalitis was studied in Macaca rhesus monkeys. Prophylactic administration of the substance under study, although not preventing the disease, modified its course and facilitated recovery of the animals. Poly(I)-poly(C) and its complex with poly-l-lysine were shown to have no effect on production of infectious virus or its antigen demonstrable by the immunofluorescence procedure in HEp-2 cells chronically infected with tick-borne encephalitis virus.

Animals↗
PubMed1979

Serological analysis of antigen-specific helper factors specific for poly-L(Tyr, Glu)-poly-DLAla--poly-LLys [(T, G)-A--L] and L Glu60-LAla30-LTyr10 (GAT).

In vitro prepared antigen-specific helper factors reactive to the synthetic polypeptide antigens poly-L(Tyr, Glu)-poly-DLAla--poly-LLys [(T, G)-A--L] or LGlu60-LAla30-LTyr10 (GAT) and bearing Ia determinants were analyzed serologically to determine the nature of the Ia determinants they expressed. I subregion-specific mouse anti-Ia antisera were used, and showed that (T, G)-A--L-specific helper factor (HF) contains I-A subregion-controlled determinants, whereas GAT-specific HF carries I-J subregion-controlled antigens. This unexptected finding was confirmed in both the H-2k and H-2 b haplotypes, using a variety of anti-I-J antisera. Rabbit anti-Ia antisera also reacted with both HF which raised the possibility that the Ia determinants on HF may be carbohydrate in nature. The fact that HF has a low molecular weight and yet contains Ia determinants, antigen-binding capacity and idiotypic markers is compatible with this interpretation.

Adsorption↗
PubMed1977

Physicochemical studies of a branched polypeptide antigen: poly(L-Tyr,L-Glu)-poly(DL-Ala)--poly(L-Lys).

The synthesis of a branched polypeptide, poly(L-Tyr,L-Glu)-poly(DL-Ala)--poly(L-Lys), is described. Physicochemical investigations of the polymer by means of hydrogen-deuterium exchange, potentiometric titrations, and viscosity measurements indicate a non-ordered, flexible conformation in aqueous solution, depending on pH and salt concentration. A hysteresis phenomenon observed in the titrations is tentatively ascribed to interactions between the sidechains, and in accordance with observations from the infrared spectrum of the polymer it is suggested that rather slow conformational changes of the polymer molecules occur in aqueous solutions. The immunochemical implications of the physiochemical findings are discussed with special reference to the concept of sequential and conformational determinants.

Alanine↗
PubMed1978

The role of H-2-linked genes in helper T-cell function. III. Expression of immune response genes for trinitrophenyl conjugates of poly-L(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys in B cells and macrophages.

Using lymph node T cells from poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys[(TG)-A--L]-primed animals and B cells from animals primed with trinitrophenylated (TNP) protein or lipopolysaccharide, we have obtained anti-TNP-(TG)-A--L direct plaque-forming responses in vitro. Response to this antigen was shown to be controlled by the H-2 haplotype of the animal studied. The strain distribution of in vitro response was very similar to that previously reported by others for in vivo secondary IgG responses to (TG)-A--L. We investigated the cell types expressing the Ir gene(s) for (TG)-A--L in our cultures. F1, high responder x low responder mice were primed with (TG)-A--L. Their T cells were active in stimulating anti-TNP-(TG)-A--L responses of high responder but not low responder B cells and macrophages (MPHI), even though both preparations of B cells and Mphi were obtained from mice congenic at H-2 with one of the parents of the F1. For three low responder strains tested, of the H-2h2, H-2k, and H-2f haplotypes, the anti-TNP-(TG)-A--L response of low responder B cells and Mphis in the presence of high responder, F1 T cells could not be improved by the addition of high responder, antigen-bearing Mphis to the cultures. In one strain of the H-2a haplotype, it was shown that neither the B cells nor Mphis could be functional in anti-TNP-(TG)-A--L responses. Our results therefore suggested the Ir genes for anti-TNP-(TG)-A--L responses were expressed at least in B cells in all the low responder strains we studied, and, in mice of the H-2a haplotype, in Mphis too.

Animals↗
PubMed1978

Identification of different antigenic determinants within the synthetic multichain Co-polymer poly(LTyr,LGlu)-poly(DLAla) -- poly (LLys), (T,G)-A--L, as recognized by the chicken. II. Fine-specificities of the anti-(T,G) part of chicken anti-(T,G)-A--L antisera.

Sera from three chickens obtained from a genetic high-responder inbred strain immunized with the multichain polypeptide poly(LTyr,LGlu)-poly-(DLAla)--poly(LLys) (T,G)-A--L) were analysed for possible restrictions in the fine-specificities of anti-(LTyr,LGlu) antibodies. A panel of synthetic hexa- and heptapeptides composed of L-Tyr and L-Glu residues linked to a C-terminal spacer tripeptide, and with L-Tyr as N-terminal, were used as inhibitors in a double-antibody radioimmunoassay. Results showed that all peptides tested possessed some inhibitional potential, although the percentage of displacement for the different sequences varied between 43% and 58%,20% and 56%, and 48% and 85%, respectively, for the three sera tested at a given inhibitor concentration. Different peptide sequences appeared as the most efficient inhibitor in the three sera tested. No simple relationship was found between substitution/elongation of inhibitor peptides and their inhibitional potential, as would have been expected from a simple conception of (T,G)-A--L possessing only one sequential determinant. Possible evidence for conformational determinants in the (T,G)-A--L antigen is discussed.

Amino Acid Sequence↗
PubMed1977

Oligopeptides as models for Tyr/Glu sequences in the multichain co-polymer poly(Lys) poly(Tyr, Glu)-poly(DL-Ala).

The syntheses of a number of oligopeptides by classical means are reported. The peptides are designed as models for possible antigenic sequences among the Tyr/Glu sequences of a macromolecule widely used as antigen in immunogenetic studies, the multichain co-polymer, poly(Lys) poly(Tyr, Glu)-poly(DL Ala). Preliminary studies on the biological activity of the oligopeptides synthesized show that only peptides with the N-terminal sequence H-Tyr-Glu- do compete with the co-polymer in a double antibody radioimmune assay, whereas other sequences do not.

Amino Acid Sequence↗
PubMed1976

Role of purine N-3 in the biologic activities of poly(A) and poly(I).

Poly(c3A) (poly 3-deazaadenylic acid) and poly(c3I) (poly 3-deazainosinic acid) differ in biological reactivity from their parent compounds poly(A) and poly(I) and from their 7-deaza counterparts poly(c7A) and poly(c7I). Three parameters of biological reactivity were evaluated : (1 degree) interferon induction, (2 degrees) anti-complement activity, (3 degrees) reverse transcriptase inhibition. Unlike poly(A)-poly(U), poly(I)-poly(C) and poly(I)-poly(br5C), the mixtures of poly(c3A) + POLY(U), poly(c3I) + poly(C), and poly(c3I) + poly(br5C) failed to elicit an interferon response in "super-induced" primary rabbit kidney cells; Poly(I) and its analogs poly(c3I) and poly(c7I) inhibited hemolytic complement activity, whereas poly(A) and its analogs poly(c3A) and poly(c7A) failed to do so. Both poly(I) and poly(c7I), but not poly(c3I), lost their anti-complement potency when annealed to either poly(C) or poly(A)-poly(U). Similarly, poly(I) and poly(c7I), but not poly(c3I), suppressed the interferon inducing ability of poly(A)-poly(U), suggesting that both poly(I) and poly(c7I), but not poly(c3I), added to poly(A)-poly(U) to form a triple-helical structure. Poly(I), poly(C7I) and poly(c7A)exerted a distinct inhibitory effect on turine leukemia virus, while under the same conditions poly(c3I) and poly(c3A) showed little, if any, inhibitory effect.

Animals↗
PubMed1978

Specific binding of poly(I)-poly(C) to the membrane of murine B lymphocyte subsets.

Indirect immunofluorescence revealed that 13% of BALB/c and 33% of CBA spleen cells of B type carry specific binding sites at their surface for double-stranded poly(I).poly(C). Pretreatment of BALB/c spleen cells with anti-mouse immunoglobulin serum increased the number of B cells capable of binding poly(I).poly(C) indicating the existence of a second B lymphocyte subpopulation carrying masked poly(I).poly(C)-binding sites. Pretreatment of the cells with mitogenic doses of either lipopolysaccharide (LPS) or single-stranded polynucleotides, e.g. poly(I) or double-stranded poly(A).poly(U), failed to affect binding of poly(I).poly(C) to the cells. Poly(I).poly(C) converts small poly(I).poly(C)-binding lymphocytes into lymphoblasts carrying poly(I).poly(C)-binding sites. Lymphoblasts derived from LPS-stimulated cells do not carry poly(I).poly(C)-binding sites. Thymocytes or splenic T cells failed to bind poly(I).poly(C). As measured by thymidine uptake, CBA mice containing a higher percentage of poly(I).poly(C)-binding cells, are high responder mice to poly(I).poly(C), compared with low responder BALB/c mice.

Animals↗