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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↗
PubMed1977

Cellular and genetic control of antibody responses in vitro. II. Ir gene control of primary IgM responses to trinitrophenyl conjugates of poly-L-(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys and poly-L-(His,Glu)-poly-D,L-Ala--poly-L-Lys.

The in vitro primary IgM anti-hapten responses to trinitrophenyl (TNP) conjugates of poly-L-(Tyr,Glu)-poly-D,L-Ala-poly-L-Lys (T,G)-A--L and poly-L(His,Glu)-poly-D,L-Ala--poly-L-Lys (H,G)-A--L were shown to be T-cell dependent and under autosomal dominant H-2-linked Ir gene control which mapped within the K or I-A regions of the H-2 complex. The in vitro response to TNP-keyhole limpet hemocyanin, while T-dependent, was not under demonstrable genetic control. The genes governing the in vitro primary IgM anti-hapten responses to TNP-(T,G)-A--L and TNP-(H,G)-A--L resemble the Ir genes controlling the in vivo secondary IgG responses to (T,G)-A--L and (H,G)-A--L in that they are autosomal dominant, map identically within the H-2 complex, and have identical responder and nonresponder haplotypes. It is concluded that Ir genes can govern the ability to generate an IgM response upon initial exposure to antigen.

Alanine↗
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

[Comparative study of the toxicity of poly G-poly C and poly I-poly C in different objects].

The poly(G).poly(C) complex has the same interferon-inducing and antiviral activity upon parenteral administration to white mice as poly(I).poly(C), but is considerably less toxic. Upon intravenous inoculation of poly(I).poly(C) to mice its LD50 is 15.8 mg/kg whereas poly(G).poly(C) is not toxic in doses up to 200 mg/kg. In rabbits inoculated with poly(I).ploy(C) intravenously its LD50 is 0.22 mg/kg, while poly(G).poly(C) is not toxic in doses of 1 mg/kg. Histological examinations of different organs of mice and rats revealed no pathomorphological changes after a single intravenous and intraperitoneal inoculation of poly(G).poly(C). It exerted no embryotoxic effect in mice in a dose of 5 mg/kg and was considerably less toxic than poly(I).poly(C) in continuous diploid cell cultures of human embryo lung cells.

Animals↗
PubMedDate not supplied

[Comparative antiviral and interferonogenic activity of synthetic polyribonucleotide complexes of poly(I).poly(C) and poly(G).poly(C) in different cell systems].

The antiviral and interferon-inducing activity of synthetic polyribonucleotide complexes poly(I)-poly(C) and poly(G)-poly(C) was studied in chick embryo, mouse embryo and rabbit kidney cell cultures. In chick embryo cell cultures both polyribonucleotides had similar antiviral activities. The interferon-inducing activity was more marked in poly(G)-poly(C) than in poly(I)-poly(C). In the other two cell cultures poly(I)-poly(C) was considerably superior in both activities. The revealed differences in the comparative activity of the polyribonucleotides in relation to the kind of tissue culture were not associated with differences between them in toxicity, sensitivity to pancreatic RN-ase or with possible differences in the duration of the contact with cells necessary for the achievement of the antiviral effect.

Animals↗
PubMed1992

Conformational aspects of poly(dI-dC).poly(dI-dC) and poly(dG-dC).poly(dG-dC) on binding of the alkaloid, berberine chloride.

Interaction of berberine chloride with poly(dI-dC).poly(dI-dC) and poly(dG-dC).poly(dG-dC) has been studied by various spectroscopic methods. Comparative data on binding parameters, fluorescence enhancement and Tm measurements indicate a stronger binding of berberine to the IC polymer than to the GC one. Conformational changes as monitored by circular dichroic spectra indicate change of the unusual circular dichroism of poly(IC) to a conformation similar to A-conformation, while in poly(GC) only a B-conformational change is observed. Extrinsic CD bands developed in the visible absorption region of berberine on interaction with poly(IC) are of much higher intensity compared to poly(GC). It is concluded that berberine induces a conformational change similar to the A-conformation on binding to poly(IC).

Berberine↗
PubMedDate not supplied

[Study of the intermolecular association of poly(G).poly(c) and poly(dG).poly(dC) in solutions by methods of 1H to 3H exchange and electron microscopy].

The kinetic of 1H leads to 3H exchange between water and C(8)H-groups of the guanylic residues in poly(G) . poly(C) and poly(dG) . poly(dC) was investigated within the temperature range from 30 to 90 degrees in 0.5 M NaCl (pH 7.2). It was shown that the exchange in freshly dissolved preparations at temperatures lower than 50 degrees proceeds faster than that in the case of GMP. According to the ylide mechanism of the exchange reaction the observed acceleration of the exchange is considered as a consequence of associates formation in poly(G) . poly(c) and poly(dG) . poly(dC) solutions at temperatures lower than 50 degrees. Associates are stabilized by intermolecular hydrogen bonds in which N(7) atoms of guanylic residues take part. The increase of the temperature is accompanied by gradual disappearance of the exchange acceleration. The retardation of exchange, which is characteristic of most non-associated double-stranded polynucleotides and nucleic acids is observed at the temperatures above 60 degrees. The retardation points to thermal destruction of the associates at temperatures higher than 50 degrees. The associates which are characterized by ordered structure including several "side by side" arranged double-stranded molecules were observed by electron microscopy. The addition of EDTA to solutions as well as the increase of temperature leads to destruction of the associates whereas the addition of Mg2+ makes the associates more stable.

Chemical Phenomena↗
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↗
PubMed1976

Triple-helical polynucleotides. Mixed triplexes of the poly(uridylic acid)-poly(adenylic acid)-poly(uridylic acid) class.

By the techniques of interferon induction in primary rabbit kidney cells "superinduced" with metabolic inhibitors, ultraviolet absorbance-temperature profiles, sensitivity to pancreatic ribonuclease A, and sucrose velocity gradient ultracentrifugation, a number of reactions between double-helical RNA and single-stranded RNA or DNA homopolymers were investigated. The polymers involved in these studies were poly(adenylic acid), poly(uridylic acid), poly(ribothymidylic acid), poly(5-bromouridylic acid), poly(deoxythymidylic acid), poly(deoxyuridylic acid), poly(3-methyluridylic acid), poly(2'-O-methyluridylic acid), and poly(2'-azido-2'-deoxyuridylic acid). Two different reaction courses, both leading to the formation of triple helices, were noted: (1) poly(Ux)-poly(A) + poly(Uy) leads to poly(Ux)-poly(A)-poly(Uy) if the Tm of poly(Ux)-poly(A) was higher than the Tm of poly(Uy)-poly(A); (2) poly(Ux)-poly(A) + poly(Uy) leads to poly(Uy)-poly(A)-poly(Ux) if the Tm of poly(Ux)-poly(A) was lower than the Tm of poly(Uy)-poly(A). In these equations, the homopolymer written to the left of poly(A) implies Watson-Crick hydrogen bonding whereas the polymer to the right of poly(A) is involved in Hoogsteen hydrogen bonding.

Animals↗
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↗
PubMed1976

Preparation and properties of an analogue of poly(A) and poly(G): poly(isoguanylic acid).

Isoguanosine-5'-pyrosphosphate, in the presence of an oligonucleotide primer, was polymerized by Escherichia coli polynucleotide phosphorylase under conditions analogous to those required for polymerization of 5'-GMP. The resulting poly(isoguanylic acid), poly(isoG), was a multistranded helix with a stability considerably higher than that of poly(G), and fully resistant to various nucleolytic enzymes. The polymer exhibited a two-step temperature transition profile in moderately alkaline propylene glycol. Alkaline titration in aqueous medium, by ultraviolet and circular dichroism spectroscopy, showed two clearly defined transitions, the second of which was fully cooperative. The accompanying changes in sedimentation constants were consistent with a structure for poly(isoG) of a fourstranded helix, like neutral poly(G). In acid medium, spectral and potentiometric titrations demonstrated the existence of more than one transition in the pH range 6-12, with accompanying protonation of the isoguanosine residues. In neutral medium the polymer formed no complexes with other potentially complementary homopolymers. In acid medium, on the other hand, the protonated form of poly(isoG) did form a triple-stranded complex with poly(I), viz. 2poly(I) . poly(isoG)+. Possible structures are formulated for the neural and protonated forms of poly(isoG) which account for the two-step thermal transition in alkaline propylene glycol and on alkaline titration in aqueous medium. The nature of the protonated form, and its complex with poly(I) is also discussed.

Binding Sites↗
PubMed1976

Newcastle disease virus-specific RNA: poly(A)-containing and poly(A)-deficient transcripts as revealed by chromatography on poly(U)-sepharose.

Total [3H]uridine-labeled, virus-specific RNA from Newcastle disease virus-infected cells was fractionated by poly(U)-sepharose chromatography and analyzed by rate zonal gradient centrifugation. The sedimentation pattern of both eluted and nonadsorbed RNA resembled that of the total RNA. However, nonadsorbed RNA was enriched in 50S material, ant its 18S peak was broader and slightly shifted towards the top of the gradient. Poly(U-sepharose chromatography of isolated 18S RNA and 24S RNA resulted in the separation of poly(A)-containing RNA and poly(A)-deficient RNA. In the former the percentage of adenosine content represented by poly(A) sequences was estimated as 10 to 12% (for 18S RNA) or approximately 6.0% (for 24S RNA). The size of poly(A) fragments as measured by their sedimentation rate was the same for 18S and 24S RNA. Polyacrylamide gel electrophoresis of poly(A)-containing RNA revealed a characteristic pattern closely resembling the pattern of nonchromatographed 18S and 24S RNA. The pattern of poly(A)-deficient RNA was heterogenous, and for 18S RNA it shifted towards the anode. The possible origin of poly(A)-deficient transcripts is discussed.

Base Sequence↗
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

Analysis of the role of different cell types in the genetic regulation of antibody production to the thymus-independent synthetic polypeptide poly (DTyr, DGlu)-poly (DPro)--poly (DLys).

The immune response potential of mice to the thymus-independent synthetic polypeptide poly (DTyr, DGlu)-poly(DPro)--poly(DLys)[D(T,G)-Pro--L] is genetically regulated. The defect in the ability of low responder mice to mount an immune response to this antigen appears to be expressed in their B cell population since the presence of thymocytes, or addition of "educated T cells" or supernatant of T cells after stimulation with the antigen neither enhanced, nor suppressed the level of antibodies produced in both low and high responder mice. Low responsiveness could not be enhanced either by stimulation of macrophages or by injection of poly(A) - poly(U) in contrast to the significant effect of these agents on low responses to the thymus-dependent poly(LTyr, LGlu)-poly(LPro)--poly(LLys) [L(T,G)-Pro--L]. These results suggest that macrophages do not participate in the limiting step, or are not involved at all, in antibody production towards the thymus-independent polypeptide. The antibodies produced in response to D(T,G)-Pro--L were found to be mainly of the 7 S class. T cells are not required for the production of mercaptoethanol resistant antibodies to this immunogen since they were found in intact mice as well as in T cell depleted animals.

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↗