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B J Sutton

Publications and source records attributed to B J Sutton.

68 records · Page 4Linked to original sources
PubMed1988

Antigen recognition by B cells: antibody-antigen interactions at the atomic level.

Despite the wealth of information concerning the structure of the antibody-combining site and the interactions involved in the binding of small molecule haptens, there is considerable debate about the way in which antibodies recognize and bind to the surfaces of foreign proteins. Two recent crystallographic analyses of antibody molecules complexed with protein antigens have provided the first glimpses of the nature of this interaction at the atomic level.

Antigen-Antibody Complex↗
PubMed1987

An X-ray-crystallographic study of beta-lactamase II from Bacillus cereus at 0.35 nm resolution.

Crystals of beta-lactamase II (EC 3.5.2.6., 'penicillinase') from Bacillus cereus were grown with Cd(II) in place of the natural Zn(II) cofactor and stabilized by cross-linking with glutaraldehyde. Their space group is C2, the cell dimensions are a = 5.44 nm, b = 6.38 nm, c = 7.09 nm and beta = 93.6 degrees, and there is one molecule in the asymmetric unit. Diffraction data were collected from cross-linked crystals of the Cd(II)-enzyme, the apoenzyme and six heavy-atom derivatives. The electron-density map calculated at 0.35 nm resolution reveals the essential Cd(II) ion surrounded by three histidine residues and one cysteine residue. The position of a glutamic acid residue, modification of which destroys activity [Little, Emanuel, Gagnon & Waley (1986) Biochem. J. 233, 465-469], suggests the probable location of the active site of the enzyme. Two minor Cd(II) sites not essential for activity were also located. The structure of the apoenzyme at this resolution appears to differ from that of the Cd(II)-enzyme only in the orientation of two of the histidine residues and the cysteine residue that surround the metal ion.

Apoenzymes↗
PubMed1986

Modelling of the combining sites of three anti-lysozyme monoclonal antibodies and of the complex between one of the antibodies and its epitope.

Models of the antigen combining sites of three monoclonal antibodies, which recognise different but overlapping epitopes within the 'loop' region of hen egg lysozyme (HEL), have been generated from the cDNA sequences of their Fv regions (the VL and VH domains) and the known crystal structures of immunoglobulin fragments. The alpha-carbon backbone of the structurally conserved framework region has been derived from the IgG myeloma protein NEW, and models for the hypervariable loop regions have been selected on the basis of length and maximum sequence homology. The model structures have been refined by energy minimisation. Both the size and chemical nature of the predicted combining site models correlate broadly with the epitope boundaries previously determined by affinity studies. A model of the complex formed between one antibody and the corresponding lysozyme epitope is described, and contact residues are identified for subsequent testing by oligonucleotide-directed site-specific mutagenesis.

Animals↗
PubMed1979

Crystallization of the Fv fragment of mouse myeloma protein M315.

The Fv fragment of mouse myeloma protein M313 was crystallized from poly(ethylene glycol) solution in the form of monoclinic crystals, space group C2 and unit cell dimensions a = 5.96 nm (59.6 A), b = 5.66 nm (56.6 A), c = 13.79 nm (13.9 A) and beta = 99.7 degrees. Some unusual effects of poly(ethylene glycol)on protein crystals were noted and are discussed.

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↗
PubMedDate not supplied

Association of rheumatoid arthritis and primary osteoarthritis with changes in the glycosylation pattern of total serum IgG.

Rheumatoid arthritis (RA) is a widely prevalent (1-3%) chronic systemic disease thought to have an autoimmune component; both humoral and cellular mechanisms have been implicated. Primary osteoarthritis (OA) is considered to be distinct from rheumatoid arthritis, and here damage is thought to be secondary to cartilage degeneration. In rheumatoid arthritis, immune complexes are present that consist exclusively of immunoglobulin, implying that this is both the 'antibody' (rheumatoid factor [RF]) and the 'antigen' (most commonly IgG). Autoantigenic reactivity has been localized to the constant-region (C gamma 2) domains of IgG. There is no evidence for a polypeptide determinant but carbohydrate changes have been reported. We have therefore conducted a study, simultaneously in Oxford and Tokyo, to compare in detail the N-glycosylation pattern of serum IgG (Fig. 1) isolated from normal individuals and from patients with either primary osteoarthritis or rheumatoid arthritis. The results, which required an evaluation of the primary sequences of approximately 1,400 oligosaccharides from 46 IgG samples, indicate that: (1) IgG isolated from normal individuals, patients with RA and patients with OA contains different distributions of asparagine-linked bi-antennary complex-type oligosaccharide structures, (2) in neither disease is the IgG associated with novel oligosaccharide structures, but the observed differences are due to changes in the relative extent of galactosylation compared with normal individuals. This change results in a 'shift' in the population of IgG molecules towards those carrying complex oligosaccharides, one or both of whose arms terminate in N-acetylglucosamine. These two arthritides may therefore be glycosylation diseases, reflecting changes in the intracellular processing, or post-secretory degradation of N-linked oligosaccharides.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Tertiary structural similarity between a class A beta-lactamase and a penicillin-sensitive D-alanyl carboxypeptidase-transpeptidase.

beta-Lactam antibiotics--the penicillins, cephalosporins and related compounds--act by inhibiting enzymes that catalyse the final stages of the synthesis of bacterial cell walls. Recent crystallographic studies of representative enzymes are beginning to reveal the structural bases of antibiotic specificity and mechanism of action, while intensive efforts are being made to understand the beta-lactamase enzymes that are largely responsible for bacterial resistance to these antibiotics. It has been suggested that the beta-lactamases and beta-lactam target enzymes may be evolutionarily related and some similarity of amino-acid sequence around a common active-site serine residue supports this idea. We present here the first evidence from a comparison of three-dimensional structures in support of this hypothesis: the structure of beta-lactamase I from Bacillus cereus is similar to that of the penicillin-sensitive D-alanyl-D-alanine carboxypeptidase-transpeptidase from Streptomyces R61.

Carboxypeptidases↗