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  • 1
    ISSN: 1573-4943
    Schlagwort(e): hemoglobin ; α chain ; antigenic structure ; antigenic site ; synthetic peptides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A comprehensive synthetic approach consisting of a series of consecutive, uniform overlapping peptides encompassing the entire protein chain was recently used to determine the full antigenic profile of the α-chain of human hemoglobin (Hb). The peptides synthesized enabled the localization of five major “continuous” antigenic regions within the α chain. The present findings describe the delineation of an antigenic site (site 2) residing within the region 41–65. Ten peptides representing the α-chain regions 41–55, 51–65, 45–54, 45–56, 45–58, 45–60, 48–56, 49–56, 50–56, and 51–56 were synthesized and purified. Quantitative radioimmunoadsorbent titrations were used to determine binding to peptide adsorbents of radioiodinated anti-Hb antibodies that were raised in rabbit, goat, and outbred mouse. In one set of peptides, the N-terminal was fixed while the C-terminal end was increased by increments of two residues from Gln-54 to Lys-60 (i.e., peptides 45–54, 45–45, 45–58, and 45–60). Binding studies revealed that maximum antibody activity resided in peptide 45–45, indicating that Lys-56 marks the C-terminal boundary of the site. In the second set of peptides, the C-terminal was fixed at Lys-56 while the peptides were elongated at their N-terminal by one-residue increments from Gly-51 to Leu-48. Antibody-binding studies with these peptides indicated that Ser-49 defines the N-terminal boundary of the site. Therefore, the antigenic site within region 41–65 of the α chain comprises residues 49–56. The relevance of these findings to the immune recognition of Hb and other proteins is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-4943
    Schlagwort(e): Monoclonal antibody ; synthetic peptide ; hemoglobin ; amino acid substitution ; antigenic site
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract It is often assumed that amino acid substitutions outside a protein antigenic site have no effect on the reactivity of a protein variant with antibodies, especially monoclonal antibodies (mAbs). Substitutions that exert an effect on the reactivity of a protein variant with mAbs are frequently considered to be within the antigenic site of the mAb. To test this assumption, two mAbs [IgGl(k) and IgG2a (k)] were prepared by immunization with a synthetic peptide corresponding to region 63–78 of the α chain of human hemoglobin (Hb). The peptide was used as an immunogen in its free form (i.e., without conjugation to a carrier), so that the results will not be made ambiguous by peptide modification nor by an immune response to sites spanning peptide and protein carrier. In addition to their reaction with human Hb, the mAbs were also studied with four primate Hbs which had no substitutions within region α63–78 and only a limited number of substitutions which occurred outside of, and at considerable distances in three-dimensional (3D) structure from, this region. Inhibition studies revealed substantial differences in the binding affinities of some of the primate Hbs, relative to human Hb. Some of the substitutions caused major decreases in binding, although they were at considerable distances in the 3D structure from the indicated site residues. It is concluded that substitutions in a protein, even when distant from an antigenic site, can exert major influences on the protein's reactivity with anti-site mAbs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-4943
    Schlagwort(e): Human red cell ; cytosol ; hemoglobin ; thyroid hormone receptor ; nonhemoglobin protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Radiolabeled thyroid hormones were allowed to bind to erythrocyte cytosol and the complex was fractionated by Sephadex G-100 or by high-performance liquid chromatography (HPLC). On Sephadex G-100, four radioactive peaks (P1∼P4) were obtained, whereas HPLC gave only three radioactive peaks (P1∼P3). Chromatographic studies with human adult Hb and non-Hb cytosol protein fractions, which had been reacted with radiolabeled thyroid hormones, and immune precipitation with specific antisera for the hormones, confirmed that the first peak of Sephadex G-100 radioactivity was a mixture of Hb and non-Hb proteins, while the second peak was Hb. The third peak was free125I and the fourth peak was unbound125I-T3 or125I-T4. The third peak of HPLC was confirmed to be a mixture of free125I and unbound radiolabeled thyroid hormones. Scatchard analysis of the interaction between T4 and apo-Hb, and the α- and β-chains of human Hb suggested the presence of the specific binding site(s) for the hormone. Interaction between T4 and synthesized peptides, which constitute the heme pocket of the β-chain of Hb (β61–75, β71–85, β81–95), indicated that the T4 binding site of Hb resides within the heme-binding cavity. It is concluded that human erythrocyte cytosol does not contain “receptor” for thyroid hormones and cannot be a model for studying functions of cytosol “receptor” for the hormones; rather, it contains binding protein with large binding capacity, including Hb and non-Hb proteins, which possibly constitute a large reservoir for the hormone in blood.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The protein journal 8 (1989), S. 767-778 
    ISSN: 1573-4943
    Schlagwort(e): hemoglobin ; synthetic peptide ; fecal occult blood ; species identification ; antibodies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Four peptides (7–16 residues) representing nonconserved regions of human hemoglobin (Hb) were selected for synthesis by comparison of the amino acid sequence of human Hb with those of the most common domesticated animals. Mouse antisera resulting from immunization with the synthetic peptides were investigated for binding to a panel of animal Hbs using solid-phase radioimmunoassay (RIA). One of the peptides elicited antibodies which bound specifically to human Hb, but not to any Hb of the nonprimate animals tested. The results show that the peptide immunogen chosen on the basis of dissimilarity between regions of different species is useful for the generation of species-specific antibodies. Such antibodies could serve as valuable tools for clinical screening of fecal occult blood trait and for forensic identification of bloodstains of human origin.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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