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Biomedical subjects

D Givol

Publications and source records attributed to D Givol.

At least 145 records · Page 8Linked to original sources
PubMed1978

The binding of 2,4,6-trinitrophenyl derivatives to the mouse myeloma immunoglobulin A protein MOPC 315.

The binding of Tnp (2,4,6-trinitrophenyl) derivatives to the Fv fragment (variable region of heavy and light chains) of the mouse myeloma IgA protein MOPC 315 was investigated by 270MHz proton nuclear magnetic resonance. Two of the haptens, Tnp-glycine and Tnp-l-aspartate, are in fast exchange with the Fv fragment, and the changes in chemical shifts for both protein and hapten resonances were determined by titrations. For the tightly binding hapten epsilon-N-Tnp-alpha-N-acetyl-l-lysine, which is in slow exchange with the Fv fragment, the changes in chemical shifts for the hapten H(3)+H(5) resonances were determined by cross-saturation. By using these data and the known structure of the combining site of protein MOPC 315 [Dwek, Wain-Hobson, Dower, Gettins, Sutton, Perkins & Givol (1977), Nature (London) 266, 31-37] the mode of binding of Tnp derivatives is deduced by ring-current calculations. The trinitrophenyl ring stacks with tryptophan-93(L) (light chain) in the ;aromatic box' formed by tryptophan-93(L), tyrosine-34(L) and phenyl-alanine-34(H) (heavy chain). Further evidence for the stacking interaction with a tryptophan residue is provided by the similarity of the optical-difference spectra observed with Tnp-aminomethylphosphonate in the presence of either the Fab fragment (light chain and N-terminal half of heavy chain) of protein MOPC 315 or tryptophan. These data show that the modes of binding of all the Tnp derivatives are very similar, despite a 100-fold range in their affinities. It is also concluded that the modes of binding of Dnp (2,4-dinitrophenyl) and Tnp derivatives to protein MOPC 315 are very similar, and that the structural basis for this is that the aromatic box is large enought to allow the trinitrophenyl ring to stack with tryptophan-93(L) while still forming hydrogen bonds to asparagine-36(L) and tyrosine-34(L).

Animals↗
PubMed1978

Selective participation of immunoglobulin V region and major histocompatibility complex products in antigen binding by T cells.

Antigen-binding inhibition studies using microscopic autoradiography were performed on T or B cell-enriched lymphocyte populations. Antibodies specific for the "framework" of immunoglobulin heavy or light chain variable domains (VH or VL), or anti-H-2 and anti-Ia antisera were used. T cell subclasses were separated with anti-Lyt antisera and complement. It was found that antigen-binding T cells of different subclasses can be inhibited selectively with only one of the two anti-V region antibodies. Antigen binding to Lyt-1+ cells was inhibited by anti-VH, while Lyt-2+,3+ cells were inhibited by anti-VL specifically. Anti-Ia antisera inhibited unprimed Lyt-1+ antigen-binding cells, whereas anti-H-2K or anti-H-2D anti-sera inhibited unprimed Lyt-2+,3+ antigen-binding cells, and both classes of immune T antigen-binding cells.

Animals↗
PubMed1977

The gross architecture of an antibody-combining site as determined by spin-label mapping.

1. A series of Dnp (dinitrophenyl) nitroxide spin labels was used to map the dimensions of the combining site of the Dnp-binding immunoglobulin A myeloma protein MOPC 315. The method compares the observed e.s.r. (electron-spin-resonance) hyperfine splittings with those calculated on the basis of different postulated motions for the spin label. The analysis is complicated by the sensitivity of the e.s.r. hyperfine splitting to the overall ;tumbling' time of the antibody-hapten complex and the polarity of the spin-label's environment. When these effects are considered quantitatively, it is then possible to determine the degree of mobility of each hapten which is allowed by the shape of the combining site. 2. The dinitrophenyl ring is rigidly held, and the depth of the site is 1.1-1.2nm and has lateral dimensions at the entrance to the site >/=0.6nmx0.9nm. The analysis of the results for spin-labelled haptens with chiral centres allows these lateral dimensions to be refined to 0.8nm and 1.1nm, and it is shown that the site is asymmetric with respect to the plane of the dinitrophenyl ring. 3. A polarity profile of the combining site was also obtained and a positively charged amino acid residue, possibly arginine-95(L) (light chain), was located at the entrance to the site. 4. The binding of Gd(III) to the antibody-hapten complexes results in quenching of the e.s.r. signal of the nitroxide. By using La(III) as a control, the paramagnetic contribution to the quenching is measured. 5. Analysis of the differential quenchings of the enantiomers of two five-membered nitroxide ring spin labels gives two possible locations of the metal-binding site. One of these is equidistant (0.7nm) from each of the three dinitrophenyl aromatic protons, and nuclear-magnetic-resonance relaxation studies, at 270MHz, on solutions of dinitrobenzene, Gd(III) and the Fv fragment (variable region of heavy and light chain) from protein MOPC 315 support this location for the metal site. 6. The e.s.r. and metal-binding data were then compared with the results of a model of the combining site constructed on the basis of framework invariance in immunoglobulins [Padlan, Davies, Pecht, Givol & Wright (1976) Cold Spring Harbor Symp. Quant. Biol.41, in the press]. The overall agreement is very good. Assignments of possible chelating groups for the metal can be made.

Binding Sites, Antibody↗
PubMed1977

Comparison of the dimensions of the combining sites of the dinitrophenyl-binding immunoglobulin A myeloma proteins MOPC 315, MOPC 460 and XRPC 25 by spin-label mapping.

The mouse immunoglobulin A myeloma proteins MOPC 315, MOPC 460 and XRPC 25 all possess dinitrophenyl (Dnp)-binding activity. Differences in specificities were shown by measuring the affinities of a variety of haptens. By using a series of Dnp-spin-labelled haptens, the dimensions of the binding sites of the three myeloma proteins were compared by the method described for protein MOPC 315 [Sutton, Gettins, Givol, Marsh, Wain-Hobson, Willan & Dwek (1977) Biochem. J.165, 177-197]. The dinitrophenyl ring is rigidly held in all three sites. The depths of the sites are all 1.1-1.2nm, but there are differences in the lateral dimensions at the entrance to the sites. For protein XRPC 25 these dimensions are 0.75nmx0.8nm, which may be compared with 0.85nmx1.1nm for protein MOPC 315 and >/=1.0nmx1.1nm for protein MOPC 460. The site in protein MOPC 460 is more symmetrical with respect to the plane of the dinitrophenyl ring than in either of the other two myeloma proteins and also allows greater penetration of solvent. In protein XRPC 25 a positively charged residue was located at the entrance to the site, similarly positioned to that reported for protein MOPC 315 [Sutton, Gettins, Givol, Marsh, Wain-Hobson, Willan & Dwek (1977) Biochem.J.165, 177-197]. All three proteins possess lanthanide-binding sites, but only in protein MOPC 315 is there antagonism between lanthanide and hapten binding. However, the effects of the diamagnetic La(III) on the electron-spin-resonance spectra of bound Dnp spin labels in both proteins MOPC 460 and XRPC 25 suggest an interaction between the two sites. Comparison of this effect with that caused by the addition of the paramagnetic Gd(III) enables the distance between the lanthanide- and hapten-binding sites to be calculated. In both proteins MOPC 460 and MOPC 315 the metal site is approx. 1.0nm from the nitroxide moiety of the spin-labelled hapten, but in protein XRPC 25 this distance is at least 2.0nm.

Antibody Specificity↗
PubMed1977

The combining site of the dinitrophenyl-binding immunoglobulin A myeloma protein MOPC 315.

Magnetic-resonance techniques are used to refine the model of the combining site of the Fv fragment of the dinitrophenyl-binding mouse myeloma protein MOPC 315 constructed by Padlan, Davies, Pecht, Givol & Wright (1976) (Cold Spring Harbor Symp. Quant. Biol.41, in the press). Light-absorption studies indicate a dinitrophenyl-tryptophan interaction in the Fv fragment of the type occurring in free solution. The Dnp-aspartate-tryptophan complex is therefore used as a starting point for the n.m.r. (nuclear-magnetic-resonance) analysis of the dinitrophenyl-Fv fragment interaction. Ring-current calculations are used to determine the geometry of the complex. The specificity of complex-formation between dinitrophenyl and tryptophan is confirmed by the lack of ring-current shifts of the dinitrophenyl resonances when tryptophan is replaced by any other aromatic amino acid. Proton n.m.r. difference spectra (at 270MHz), resulting from the addition of a variety of haptens to the Fv fragment, show that the combining site is highly aromatic in nature. Calculations on the basis of ring-current shifts define the geometry of the combining site, which involves a dinitrophenyl ring in van der Waals contact with four aromatic amino acid residues on the protein. The observation of a nuclear Overhauser effect on the H((3)) resonance of the dinitrophenyl ring provides additional constraints on the relative geometry of the H((3)) proton and an aromatic amino acid residue on the Fv fragment. The specificity of the Fv fragment for dinitrophenyl ligands arises from a stacking interaction of the dinitrophenyl ring with tryptophan-93(L), in an ;aromatic box' of essentially tryptophan-93(L), phenylalanine-34(H) and tyrosine-34(L); asparagine-36(L) and tyrosine-34(L) also contribute by forming hydrogen bonds with the nitro groups on the dinitrophenyl ring. The n.m.r. results also confirm that the antibody-hapten reaction may be visualized as a single encounter step. An Appendix shows the method of calculation of ring currents for the four aromatic amino acids and their use in calculating structures.

Binding Sites, Antibody↗
PubMed1977

Specificity of interactions of hapten side chains with the combining site of the myeloma protein MOPC 315.

The pKa values of the three histidine residues in the Fv fragment (variable region of the heavy and light chains) of the mouse myeloma protein MOPC 315, measured by high resolution n.m.r. (nuclear magnetic resonance), are 5.9, 6.9 and 8.2. The perturbation of the pKa of one of the histidines (pKa 6.9) on the addition of hapten and the narrow linewidth of its proton resonances suggests that it is at the edge of the combining site. References to the model of the Fv fragment [Padlan, Davies, Pecht, Givol & Wright (1976) Cold Spring Harbor Symp. Quant. Biol. 41, in the press] allows assignment of the three histidine residues, histidine-102H, histidine-97L and histidine-44L. The determination of the pKa of the phosphorus group, by 31P n.m.r., of a homologous series of Dnp- and Tnp- (di- and tri-nitrophenyl) haptens has located a positively charged residue. Molecular-model studies on the conformations of these haptens show that the residue is at the edge of the site. The model suggests that the positively charged residue is either arginine-95L or lysine-52H.

Antibody Specificity↗
PubMed1977

Structure of an antibody combining site by magnetic resonance.

The structure of the combining site of the DNP binding IgA mouse myeloma protein MOPC 315 has been determined by a combination of high resolution nuclear magnetic resonance, electron spin resonance, model building and chemical modifications. This approach yields that general dimensions of the site, its polarity and asymmetry features, the assignment of the DNP-contact residues and their three-dimensional coordinates.

Animals↗
PubMed1977

On the location of palindromes in immunoglobulin genes.

We present a statistical method for detection of palindromes in mRNA or DNA, starting from the protein sequence. Analysis of immunoglobulin genes by this method demonstrates that palindromic sequences are not randomly distributed. They are located at each side of the hypervariable regions in the variable (V) genes, whereas no such regular design is observed in the constant (C) genes. In addition, palindromic sequences overlap the V-C junction in all immunoglobulin classes and significant palindromes are present near residue 216 of the heavy chain, which is the end of deletions in many heavy chain diseases. The relevance of these palindromes to gene translocation and generation of diversity in antibodies is discussed.

Base Sequence↗