Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “bivalent”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources
PubMed1999

Design and evaluation of novel bivalent thrombin inhibitors based on amidinophenylalanines.

Two bivalent thrombin inhibitors were synthesized, which consist of a benzamidine-based active-site-blocking segment, a fibrinogen recognition exosite inhibitor and a peptidic linker connecting these fragments. BZA-1 hirulog contains an Nalpha-(2-naphthylsulfonyl)-S-3-amidinophenylalanyl-is onipecotic acid residue connected via the carboxyl group to the linker segment. The active-site-directed moiety of BZA-2 hirulog [Nalpha-(2-naphthylsulfonyl-glutamyl)-R-4-amidinophenylal anyl-piperid ide] was coupled to the linker via the side chain of the glutamic acid. Both BZA-hirulogs contain almost identical linker-exo site inhibitor parts, except for the substitution of a glycine as the first linker residue in BZA-1 hirulog by a gamma-amino butyric acid in BZA-2 hirulog, thus increasing flexibility and linker length by two additional atoms. BZA-1 hirulog showed moderate potency (Ki = 0. 50 +/- 0.14 nM), while BZA-2 hirulog was characterized as a slow, tight binding inhibitor of thrombin (Ki = 0.29 +/- 0.08 pM). The stability in human plasma of both analogs was strongly improved compared with hirulog-1. For BZA-2 hirulog a significantly reduced plasma clearance was observed after intravenous injection in rats compared with BZA-1 hirulog and hirulog-1. The X-ray structure of the BZA-2 hirulog in complex with human alpha-thrombin was solved and confirmed the expected bivalent binding mode.

Amino Acid Sequence↗
PubMed2000

Organization-dependent effects of toxic bivalent ions microtubule assembly and glycolysis.

The effects of bivalent ions on tubulin dynamics and the upper phase of glycolysis were investigated at different organization levels in vitro. Cu2+, Cd2+, Hg2+ and CrO4(2-) inhibit the tubulin polymerization at an IC50 of 14-24 microM with high cooperativity and also induce microtubule disassembly. The apparent binding constants of the ions to tubulin, estimated by fluorescence quenching, vary between 6 and 28 microM. BIAcore measurements for tubulin-tubulin interaction suggest that the presence of Cu2+ affects neither koff nor kon, but the amount of the bound tubulin. While the inhibitory effect of Cu2+ on tubulin polymerization is partially abolished by cross-linking of microtubules with substoichiometric amounts of phosphofructokinase or decoration of tubules with cytosolic proteins, in the presence of kinase but not with cytosolic proteins the tubules are resistant to CrO4(2-). No inhibitory effect of Cu2+ or CrO4(2-) on microtubule assembly was detected in the MAP-containing cytosolic fraction. Electron microscopy revealed that tubules assembled in the presence of Cu2+ or CrO4(2-) ions contain aggregates of thread-like oligomers that are less conspicuous in the presence of cytosolic proteins. Cu2+, Cd2+, and Hg2+ inhibit the glycolytic flux in the cytosolic fraction characterized at equilibrium by an IC50 of 10-14 microM with high cooperativity. Tubulin diminishes the inhibitory effect of the cations. These data indicate that the responses elicited by the bivalent ions are highly dependent on the supramolecular organization of the systems.

Acetates↗
PubMed2001

Regulation of cystic fibrosis transmembrane conductance regulator single-channel gating by bivalent PDZ-domain-mediated interaction.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent protein kinase- and ATP-regulated chloride channel, the activity of which determines the rate of electrolyte and fluid transport in a variety of epithelial tissues. Here we describe a mechanism that regulates CFTR channel activity, which is mediated by PDZ domains, a family of conserved protein-interaction modules. The Na(+)/H(+) exchanger regulatory factor (NHERF) binds to the cytoplasmic tail of CFTR through either of its two PDZ (PDZ1 and PDZ2) domains. A recombinant fragment of NHERF (PDZ1-2) containing the two PDZ domains increases the open probability (P(o)) of single CFTR channels in excised membrane patches from a lung submucosal gland cell line. Both PDZ domains are required for this functional effect, because peptides containing mutations in either domain are unable to increase channel P(o). The concentration dependence of the regulation by the bivalent PDZ1-2 domain is biphasic, i.e., activating at lower concentrations and inhibiting at higher concentrations. Furthermore, either PDZ domain alone or together is without effect on P(o), but either domain can competitively inhibit the PDZ1-2-mediated stimulation of CFTR. Our results support a molecular model in which bivalent NHERF PDZ domains regulate channel gating by crosslinking the C-terminal tails in a single dimeric CFTR channel, and the magnitude of this regulation is coupled to the stoichiometry of these interactions.

Amino Acid Sequence↗
PubMed1996

Leucine zipper dimerized bivalent and bispecific scFv antibodies from a semi-synthetic antibody phage display library.

This report describes the construction of leucine zipper-based dimerization cassettes for the conversion of recombinant monomeric scFv antibody fragments to bivalent and bispecific dimers. A truncated murine IgG3 hinge region and a Fos or Jun leucine zipper were cloned into four scFv fragments previously isolated from a synthetic antibody phage display library. Cysteine residues flanking the zipper region were introduced to covalently link dimerized scFv fragments. The secreted fusion proteins were shown to spontaneously and efficiently form stable Fos-Fos or Jun-Jun homodimers in the Escherichia coli periplasm at levels comparable to their monovalent counterparts. The bivalent (scFv)2 fragments performed well in enzyme-linked immunosorbent assay, flowcytometric, and immunohistochemical analysis. Fos and Jun homodimer (scFv)2 antibodies with different specificities could be reduced, reshuffled, and reoxidized to form preparations of functional bispecific (scFv)2 Fos-Jun heterodimers. These Fos and Jun fusion protein cassettes provide a universal basis for the construction of dimeric scFv antibodies with enhanced avidity or dual specificity.

Amino Acid Sequence↗
PubMed1999

Bivalent inhibitor of the N-end rule pathway.

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Ubr1p, the recognition (E3) component of the Saccharomyces cerevisiae N-end rule pathway, contains at least two substrate-binding sites. The type 1 site is specific for N-terminal basic residues Arg, Lys, and His. The type 2 site is specific for N-terminal bulky hydrophobic residues Phe, Leu, Trp, Tyr, and Ile. Previous work has shown that dipeptides bearing either type 1 or type 2 N-terminal residues act as weak but specific inhibitors of the N-end rule pathway. We took advantage of the two-site architecture of Ubr1p to explore the feasibility of bivalent N-end rule inhibitors, whose expected higher efficacy would result from higher affinity of the cooperative (bivalent) binding to Ubr1p. The inhibitor comprised mixed tetramers of beta-galactosidase that bore both N-terminal Arg (type 1 residue) and N-terminal Leu (type 2 residue) but that were resistant to proteolysis in vivo. Expression of these constructs in S. cerevisiae inhibited the N-end rule pathway much more strongly than the expression of otherwise identical beta-galactosidase tetramers whose N-terminal residues were exclusively Arg or exclusively Leu. In addition to demonstrating spatial proximity between the type 1 and type 2 substrate-binding sites of Ubr1p, these results provide a route to high affinity inhibitors of the N-end rule pathway.

Binding Sites↗
PubMed2000

Camel single-domain antibodies as modular building units in bispecific and bivalent antibody constructs.

Single-domain antibodies against various antigens are isolated from the unique heavy-chain antibodies of immunized camels and llamas. These minimal sized binders are very robust and bind the antigen with high affinity in a monomeric state. We evaluated the feasibility to produce soluble, functional bispecific and bivalent antibodies in Escherichia coli with camel single-domain antibody fragments as building blocks. Two single-domain antibody fragments were tethered by the structural upper hinge of a natural antibody to generate bispecific molecules. This linker was chosen for its protease resistance in serum and its natural flexibility to reorient the upstream and downstream located domains. The expression levels, ease of purification, and the solubility of the recombinant proteins were comparable with those of the constituent monomers. The individual moieties fully retain the binding capacity and the binding characteristics within the recombinant bispecific constructs. The easy generation steps and the biophysical properties of these bispecific and bivalent constructs based on camel single-domain antibody fragments makes them particularly attractive for use in therapeutic or diagnostic programs.

Amino Acid Sequence↗
PubMed2005

Ligand-assisted aggregation of proteins. Dimerization of serum amyloid P component by bivalent ligands.

A comprehensive series of solution and crystallographic studies reveal how simple, achiral, bivalent ligands of the cyclic pyruvate of glycerol promote face-to-face complex formation of the pentraxin, serum amyloid P component (SAP) into decamers. SAP, a protein of the human innate immune system, is universally present in amyloids, including cerebral amyloid deposits found in the brain of Alzheimer disease patients. Removal of SAP through a specific aggregation mechanism mediated by multivalent ligands appears to provide therapeutic benefit in the progression of this disease. Crystallographic studies reveal that in our novel series of ligands only the methyl and carboxylate moieties of the pyruvate ketal directly interact with the protein, but the geometric constraints imposed by the tether dictate which of two chair conformations are adopted by the pyruvate dioxane ring. Solution studies, as interpreted through a simple thermodynamic model, account for the distribution of pentameric and decameric bound states at different ligand concentrations and indicate that differences in the flexibility of the tether determine the geometry and stability of the specific aggregates formed between SAP and two different bivalent ligands. The factors affecting the design of ligands promoting face-to-face protein dimerization as well as potential biological implications are discussed.

Crystallography, X-Ray↗
PubMed1976

Conjugation in Tetrahymena pyriformis. The effect of polylysine, concanavalin A, and bivalent metals on the conjugation process.

The polycation polylysine, at different degrees of polymerization, was found to cause a marked inhibition of the conjugation process. Inhibition of conjugation by polylysine was highly dependent on the molecular weight of the polymer. When polylysine of a mol wt of 1,250 (degree of polymerization=6) was used, a concentration of 1.6 X 10(-5) M was required for a complete inhibition of conjugation, while only 2 X 10(-7) M of polylysine of a mol wt of 71,000 (degree of polymerization=340) was needed for the same effect. Polyaspartic acid prevented the inhibition of conjugation by polylysein. Chelators of bivalent metals such as O-phenanthroline (10(-3) M), EDTA (10(-3) M), and EGTA (5 X 10(-3) M) strongly inhibit the conjugation process in Tetrahymena pyriformis. The inhibition was partially prevented when bivalent metals such as Zn++, Fe++, and Ca++ were added together with the chelators. The lectin concanavalin A (25 mug/ml) completely prevented the conjugation process, while other lectins, such as phytohemagglutinin (500 mug/ml), soybean agglutinin (75 mug/ml) and wheat germ agglutinin (250 mug/ml) had no effect. Inhibition of conjugation by concanavalin A is completely reversible by 40 mM of alpha-methyl-D-mannoside.

Animals↗
PubMed2003

Safety and immunogenicity of a bivalent group B streptococcal conjugate vaccine for serotypes II and III.

To determine whether 2 monovalent group B streptococcus (GBS) serotype II or III capsular polysaccharide (CPS)-tetanus toxoid (TT) conjugate vaccines combined in a single intramuscular dose would elicit immune responses comparable to those of monovalent vaccines, 75 healthy adults were randomized to receive GBS II-TT (3.6 micro g of CPS), GBS III-TT (12.5 micro g of CPS), or a bivalent mixture of GBS II-TT/III-TT vaccine (double-masked design). Vaccines were well tolerated. Four-fold or greater increases in GBS II or III CPS-specific IgG, respectively, were noted in postimmunization serum samples from 80%-90% of bivalent conjugate vaccine recipients, and these responses were similar to those of recipients of GBS II-TT or GBS III-TT monovalent vaccines. Immune serum samples promoted the opsonophagocytic killing of types II and III GBS in vitro. Unexpectedly, some recipients of these vaccines developed cross-reactive antibodies to the structurally similar heterologous polysaccharide. These results support the feasibility of a multivalent vaccine for the 5 prevalent invasive disease-causing GBS CPS serotypes.

Adolescent↗
PubMed1995

Expression of monovalent and bivalent antibody fragments in Escherichia coli.

The technology of humanization of rodent antibodies has opened the way for a broad range of therapeutic antibodies with very low immunogenicity, which are, therefore, suitable for repeated dosing. Such intact antibodies have extended serum half-lives and biodistribution profiles very similar to human antibodies. For some applications, however, the ideal therapeutic should have reduced serum half-life and altered biodistribution patterns typical of antibody fragments, such as Fab or single chain Fv. Bispecific antibody fragments offer exciting additional therapeutic possibilities, but their successful manufacture and purification on a large scale require the development of new methods. Antibody fragments often assemble in Escherichia coli as monovalent fragments with reduced affinities. We describe the spontaneous assembly of bivalent antibody fragments in E. coli and methods of purification that yield either bivalent or monovalent molecules as required.

Animals↗
PubMed2004

Thermodynamic binding studies of bivalent oligosaccharides to galectin-1, galectin-3, and the carbohydrate recognition domain of galectin-3.

Galectins are a growing family of animal lectins with common consensus sequences that bind beta-Gal and LacNAc residues. There are at present 14 members of the galectin family; however, certain galectins possess different structures as well as biological properties. Galectin-1 is a dimer of two homologous carbohydrate recognition domains (CRDs) and possesses apoptotic and proinvasive activities. Galectin-3 consists of a C-terminal CRD and an N-terminal nonlectin domain implicated in the oligomerization of the protein and is often associated with antiapoptotic activity. Because many cellular oligosaccharide receptors are multivalent, it is important to characterize the interactions of multivalent carbohydrates with galectins-1 and -3. In the present study, binding of bovine heart galectin-1 and recombinant murine galectin-3 to a series of synthetic analogs containing two LacNAc residues separated by a varying number of methylene groups, as well as biantennary analogs possessing two LacNAc residues, were examined using isothermal titration microcalorimetry (ITC) and hemagglutination inhibition measurements. The thermodynamics of binding of the multivalent carbohydrates to the C-terminal CRD domain of galectin-3 was also investigated. ITC results showed that each bivalent analog bound by both LacNAc residues to the two galectins. However, galectin-1 shows a lack of enhanced affinity for the bivalent straight chain and branched chain analogs, whereas galectin-3 shows enhanced affinity for only lacto-N-hexaose, a naturally occurring branched chain carbohydrate. The CRD domain of galectin-3 was shown to possess similar thermodynamic binding properties as the intact molecule. The results of this study have important implications for the design of carbohydrate inhibitors of the two galectins.

Binding Sites↗
PubMed1977

Serologic responses and systemic reactions in adults after vaccination with bivalent A/Victoria/75-A/New Jersey/76 and monovalent B/Hong Kong/72 influenza vaccines.

Bivalent A/Victoria/75-A/New Jersey/76 and monovalent B/Hong Kong/72 influenza vaccines were given alone or together to adutls, and systemic reactions and antibody responses were determined. The rates of systemic reactivity observed varied among vaccine groups. Disrupted vaccines and whole-virus vaccines containing type B antigen only did not cause significant reactivity. Systemic reactions were observed after administration of the bivalent A whole-virus vaccines, and this reactivity was increased if the B vaccine was also administered. Reactions to the more reactive vaccines were less frequent in older subjects or in younger individuals with evidence of previous exposure to influenza antigens in the vaccine. Antibody responses in this study indicated that individuals older than 25 years responded better to A/New Jersey antigens than did younger subjects. The A/Victoria antigen produced lower antibody levels in older individuals than in younger subjects. The B/Hong Kong antibody responses were similar in all vaccine groups.

Adolescent↗
PubMed1977

Responses of elderly and chronically ill subjects to bivalent influenza A/New Jersey/8/76 (Hsw1N1)-A/Victoria/3/75 (H3N2) vaccines.

Antibody responses and side effects to bivalent influenza A virus vaccines from three different manufacturers, containing 200 or 400 chick cell-agglutinating (CCA) units each of A/New Jersey/8/76 (Hsw1N1) and A/Victoria/3/75 (H3N2) antigens, were evaluated in 234 ambulatory elderly and chronically ill volunteers in a placebo-controlled, doubld-blind study. Systemic reactions did not occur significantly more often among recipients of vaccine than among volunteers who received placebo. Local reactions to vaccines were observed but were mild, transient, and well tolerated. Occurrence of preexisting antibody to each antigen was common. Titers of antibody to A/New Jersey/8/76 (Hsw1N1) antigen of greater than or equal to 1:40 occurred after immunization in 94%-100% of volunteers receiving vaccines and in 66% of the placebo recipients. Titers of antibody to A/Victoria/3/75 (H3N2) antigen of greater than or equal to 1:40 occurred in 53%-85% of vaccine recipients compared with 34% of those in the placebo group. Thus, bivalent split-product and whole-virus influenza I vaccines containing 200/200 or 400/400 CCA units of the two antigens appeared to be nearly equivalent in incidence and severity of side effects and antibody responses in recipients.

Adult↗
PubMed1977

Bivalent influenza vaccine in children with cancer.

Although it had been recommended that children with malignant diseases be immunized against influenza, few data were available to indicate the immune response or reactions that might be expected from this group. Forty-six children with malignant diseases received various dosages of killed split or whole bivalent (A/New Jersey/76-A/Victoria/75) influenza vaccine or a placebo by the intramuscular route. Two doses were administered four weeks apart. The children were receiving various regiments of cancer chemotherapy. The response to A/New Jersey/76 antigen in the children with malignant diseases was similar to that found in normal children who were immunized with bivalent or monovalent (A/New Jersey/76) vaccine in the National Influenza Immunization Trials. Fourteen of 26 children had antibodies to A/Victoria/75 before immunization; nine of the 12 children without these antibodies developed them after the first dose of vaccine. Adverse reactions after vaccination were minimal.

Adolescent↗
PubMed1977

Clinical trials with inactivated monovalent (A/New Jersey/76) and bivalent (A/New Jersey/76-A/Victoria/75) influenza vaccines in Los Angeles children.

Clinical and serologic responses to inactivated influenza virus vaccines were studied in 444 children in Los Angeles under doubld-blind, placebo-controlled protocols. One- and two-dose regimens employing monovalent (A/New Jersey/76) and bivalent (A/New Jersey/76-A/Victoria/75) vaccine were studied in separate trials. In a single dose, whole-virus vaccines were more potent than split-product vaccines as primary inducers of immunity against influenza A/New Jersey/76 virus. Split-product vaccines were better tolerated clinically and, after two-dose regiments, produced rates of seroconversion (greater than 90%) against A/New Jersey/76 virus comparable to those produced by two doses of whole-virus vaccines. Analysis of heterotypic antibody responses induced by monovalent A/New Jersey/76 vaccines revealed only slight increases in antibody against influenza A/Victoria/75 virus. After vaccination with bivalent vaccines, levels of antibody against influenza A/Victoria/75 virus were significantly higher in subjects who received high doses of split-product vaccines than in subjects who received whole-virus vaccines.

Adolescent↗
PubMed1977

Reactogenicity and immunogenicity of bivalent influenza A and monovalent influenza B virus vaccines in high-risk children.

Seventy-nine high-risk children were immunized with either commercial, bivalent, split-product influenza A vaccine or purified hemagglutinin-neuraminidase bivalent influenza A vaccine, and 78 of these subjects were immunized with commercial, monovalent, influenza B split-product vaccine. The reactogenicity of all three vaccines was low, and there were no severe reactions. Twenty-nine subjects who received hemagglutinin-neuraminidase vaccine as their initial dose and commercial split-product vaccine as a booster dose had significantly lower antibody responses to influenza A/New Jersey/76 virus than subjects who received two doses of commercial split-product vaccine. The responses of the two groups to influenza A/Victoria/75 virus were comparable. Twenty-four subjects with malignancy who were receiving chemotherapy were compared with a group of subjects matched for age and vaccine preparation. Patients with cancer had significantly lower antibody responses to A/New Jersey/76 virus than patients without cancer. The ultimate responses of patients with cancer to A/Victoria/75 and B/Hong Kong/72 viruses were comparable to those of other patients, but early responses were lower.

Adolescent↗
PubMed1987

Prevention of shigellosis by a Salmonella typhi-Shigella sonnei bivalent vaccine.

We genetically modified attenuated Salmonella typhi strain Ty21a to express the form I O polysaccharide antigen of Shigella sonnei. Three doses of this bivalent, live oral vaccine strain (1-8 X 10(9) organisms/dose) were given to young adults who, along with unvaccinated controls, were challenged one month later with pathogenic S. sonnei. The vaccinees had 40% protection against diarrhea and 56% against Hematest-positive diarrhea. Two of three vaccine lots provided higher levels of protection (53% against diarrhea and 71% against Hematest-positive diarrhea), but the third lot, prepared for a large-scale field trial, demonstrated no protective efficacy. Vaccinees had serum and local intestinal immune responses to S. sonnei lipopolysaccharide, and the presence of specific serum IgA or IgG antibody before challenge with pathogenic S. sonnei was correlated with protection from illness. Some lots of this bivalent vaccine strain provide significant protection against S. sonnei disease, but the problem of lot-to-lot variability must be overcome.

Adult↗
PubMed1992

Hyperthermia specifically inhibits bivalent chromosome disjunction in maturing mouse oocytes.

The effect of hyperthermia on mammalian oocyte maturation was studied by allowing preovulatory mouse oocytes to mature spontaneously for 17 h in vitro under controlled temperature conditions. At the end of culture, oocytes were screened for their maturation stage and for chromosome morphology and number. Mild hyperthermic conditions (38.5-40.0 degrees C) during maturation specifically disturbed the process of bivalent chromosome disjunction, but not other maturation steps, by blocking oocytes at the metaphase I stage and preventing cells from entering subsequent maturation steps. Some oocytes that had reached metaphase II under hyperthermic conditions had chromosome imbalance. Oocytes matured at 40.0 degrees C displayed chromosome morphological abnormalities, including altered sister chromatid separation and nucleus/nuclei formation, at a frequency significantly higher than oocytes matured at 37.0-39.0 degrees C. When incubation temperature was raised above 40.0 degrees C, increasing fractions of oocytes were inhibited from entering initial maturation steps. We conclude that hyperthermia during mammalian oocyte maturation specifically damages the process of bivalent chromosome disjunction and induces the appearance of chromosome structural defects and imbalance in unfertilized eggs.

Animals↗