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D Beale

Publications and source records attributed to D Beale.

At least 37 records · Page 2Linked to original sources
PubMed1989

Some observations on conserved polar side chains in immunoglobulin V-domains.

1. The roles of conserved polar residues have been studied in 12 V-domains for which atomic coordinates are available. 2. In most cases a particular residue had a similar side chain conformation in all V-domains examined and the polar group provided the same hydrogen bonds which helped to stabilize the conformations of the domains. 3. In the case of a conserved glutamine/glutamic acid residue the buried side chain could adopt a variety of conformations and the polar group could form different hydrogen bonds from one domain to another. However, they contributed similarly to domain stability. 4. In the case of a conserved threonine/serine residue its side chain showed relative rotations of up to 180 degrees from one domain to another. The hydroxyl group could be buried or exposed at the domain surface. In some domains it formed hydrogen bonds to two other protein atoms but in other domains there was a single hydrogen bond or none at all. The varied roles of this residue are discussed in the text.

Aspartic Acid↗
PubMed1989

Tryptic digestion of bovine secretory IgA at elevated temperature and in urea. Isolation of SC domain 1 which is covalently bound to IgA dimer and binds non-covalently to IgM.

1. Tryptic cleavage sites in bovine secretory component (SC) which become inaccessible when SC is bound to IgA dimer remained inaccessible at 60 degrees C and in 4 M urea at 37 degrees C. 2. This suggests the presence of strong interactions compatible with published affinity constants of ca 10(8) M-1. 3. In 5 M urea at 37 degrees C further cleavage of bound SC did occur to produce a fragment consisting of domain 1 which was disulphide bridged to the IgA dimer. 4. Binding studies on the isolated fragment showed that domain 1 did not account for all the binding by SC. 5. Cleavage of the isolated fragment with iodosobenzoic produced a smaller fragment consisting of the n-terminal third of domain 1 (residues 1-35). This N-terminal fragment showed significant binding.

Alkylation↗
PubMed1989

Some observations on the replacement of the conserved amino acid residues of immunoglobulin domains.

1. Computer graphics have been used to model replacements of conserved residues in immunoglobulin domains. 2. Replacements, even those involving large changes in side chain volume, could be accommodated in the domain but rotation and repacking of surrounding side chains was generally necessary. 3. Repacking often resulted in increases in inter-atomic distances between side chains and loss of some van der Waals' contacts. This would be expected to make the domain slightly less stable. 4. Losses in domain stability might not have a serious affect on antigen binding but could result in circulating antibody becoming more susceptible to biological degradation with considerable reduction in biological half-life.

Alanine↗
PubMed1989

Structure of bovine immunoglobulin constant region heavy chain gamma 1 and gamma 2 genes.

Two bovine immunoglobulin constant region gamma heavy chain germline gene sequences are described. A gamma 1 gene was cloned from a lambda 2001 calf liver library screened with a human gamma 4 (pBRH4.1) probe and is contained in a 5.8 kb BamH1 hybridizing fragment. The gamma 2 gene was from an EMBL4 lambda library and is in a 6.6 kb BamH1 fragment. Each of these genes is arranged in four exons corresponding to the three CH domains and the hinge of gamma heavy chain genes; normal RNA splice and polyadenylation sites are present. The translated C-terminal peptide sequences of the genes match exactly the equivalent peptide sequences of bovine IgG1 and IgG2 heavy chains, identifying them as gamma 1 and gamma 2. The derived protein sequences reveal 96, 80 and 83% identity of amino acid residues between their CH1, CH2 and CH3 domains. Two adjacent cysteine residues encoded in the CH1 exons suggest that, as in rabbit gamma, an extra intra-chain disulphide bond occurs in the bovine gamma heavy chains. Significant DNA rearrangement in the hinge-CH2 region is evident in the bovine gamma 2 gene, with resultant deletion and substitution of amino acid residues in the lower hinge and N-terminal portion of the CH2 domain. The Fab-Fc interface of bovine IgG2 is predicted to be sterically blocked, relative to IgG1, which has implications for effector differences between the bovine gamma subclasses.

Animals↗
PubMed1989

Preventing staff-patient sexual relationships.

Just as the awareness of incest and childhood sexual abuse has grown in recent years, so too has knowledge of sexual exploitation of patients by psychotherapists and other mental health professionals. Almost no one, however, has discussed the prevalence of this problem in the hospital setting. The authors were members of a study group that thoroughly reviewed reported incidents in their own institution, leading to the recommendation that education is the best preventive measure currently available. The authors discuss fundamental issues involved in such a study, summarize profiles of patients and staff members who may be vulnerable to sexual involvement, and describe the main components of a preventive educational approach.

Antisocial Personality Disorder↗
PubMed1988

Cyanogen bromide cleavage of bovine secretory component and its tryptic fragments.

1. Five-domain bovine secretory component and its two-domain and three-domain tryptic fragments have been treated with cyanogen bromide. 2. N-terminal sequence analysis of the purified products showed that cleavage occurred within the disulphide bridged polypeptide loop of domain 2. The site lies within the region that binds IgM and IgA dimers. 3. The relative binding of the CNBr fragments to IgM has been measured and indicates that domains 1 and 3 are directly involved. 4. A possible role for domain 2 is less clear and domains 4 and 5 do not participate in binding.

Amino Acid Sequence↗
PubMed1988

Partial amino acid sequence analysis and variable subgroup determination (VH and VL) of a monoclonal rheumatoid factor derived from a rheumatoid arthritis patient.

Continuous cell lines secreting monoclonal rheumatoid factors (RF) were derived from rheumatoid arthritis (RA) patients by cloning Epstein-Barr virus (EBV) transformed B cells and by hybridoma techniques. We studied five different clones with stable RF secretion. All were IgM, 4 kappa and 1 lambda. One of these clones, RFAN was extensively studied, and the partial amino acid sequences of the variable regions of both heavy and light chains were determined. After affinity purification, the IgM lambda RF antibody derived from the EBV clone was run under reducing conditions on SDS-polyacrylamide gel electrophoresis. The separated heavy and light chains were blotted and then sequenced by a gas-phase sequenator. The N-terminal sequence of the lambda light chain corresponded to that of the V lambda III subgroup. The heavy chain of the same IgM RF clone had a blocked N-terminus, but a cyanogen bromide peptide starting after methionine at position 82 showed a sequence typical of the VHIII subgroup. Heavy and light chains were also prepared by gel filtration after reduction and carboxymethylation from the same EBV clone made into a hybridoma. After this preparation, the heavy chain was not blocked and the N-terminal sequence confirmed that the heavy chain variable region belonged to the VHIII subgroup. We believe this to be the first amino acid sequence study of a monoclonal RF derived from the repertoire of an RA patient.

Amino Acid Sequence↗
PubMed1987

The sites of tryptic cleavage in bovine secretory component: structural and functional implications.

Tryptic fragments from bovine secretory component and sIgA have been separated by HPLC and/or SDS polyacrylamide gel electrophoresis and electroblotting. Their N-terminal amino acid sequences have been determined and their positions in the secretory component molecule deduced by homology with the amino acid sequences of human secretory component and rabbit polyimmunoglobulin receptor. Taken in conjunction with the known binding affinities of the tryptic fragments, the results imply that the three most N-terminal domains of secretory component are directly involved in binding IgM and IgA dimers. The results also favour the concept of an extended 'zig-zag' structure for the secretory component molecule.

Amino Acid Sequence↗
PubMed1987

The binding of an aminoazo dye carcinogen to a specific methionine residue in rat liver alcohol dehydrogenase in vivo.

On the administration of 3'-methyl-N,N-dimethyl-4-aminoazobenzene to rats pure aminoazo dye-bound alcohol dehydrogenase accounting for 45% of the total soluble protein bound aminoazo dye is isolated from the liver soluble supernatant. Tryptic digestion of that purified aminoazo dye-bound enzyme yields an aminoazo dye-bound nonapeptide which has a sequence identical to amino acids 301-309 in the known sequence of alcohol dehydrogenase (H. Jornvall and O. Markovic, Eur. J. Biochem., 29 (1972) 167-174) with the exception of methionine 306 which is replaced by an aminoazo dye modified amino acid. The nature of the aminoazo dye adduct was determined by studying the structure of the related tetrapeptide obtained by Pronase B digestion and shown by proton NMR spectroscopy and fast atom bombardment mass spectroscopy to have the structure 3-(Val. Asn. Pro. Homocystein-S-yl)-4-methylamino-3'-methylazobenzene. This carcinogen-protein adduct is assumed to arise from attack of the ultimate carcinogenic metabolite, N-sulphonyloxy-4-methylamino-3'-methylazobenzene (FF. Kadlubar, J.A. Miller and E.C. Miller, Cancer Res., 36 (1976) 2350-2359) at the sulphur of methionine 306 followed by spontaneous S-demethylation. This highly specific reaction of carcinogen with alcohol dehydrogenase lowers its Vmax and increases its Km with cyclohexanone thereby reducing its catalytic efficiency for this substrate. This highly specific reaction of the carcinogen with alcohol dehydrogenase may be regarded as a major detoxication reaction.

Alcohol Dehydrogenase↗
PubMed1987

The structure of bovine secretory component.

Bovine secretory component (SC) has been cleaved with trypsin into a series of fragments and their N-terminal amino acid sequences have been determined. The close homology with the known sequence of human SC has enabled the sequential order of the fragments to be deduced. The results indicate that bovine SC consists of a single glycosylated polypeptide chain (Mr 74,000) folded into five globular immunoglobulin-like domains. A protein (Mr 94,000) has been isolated from detergent solubilised bovine epithelial membranes from liver, intestine and mammary gland. This membrane protein is specific for the binding of J-chain linked IgM and IgA dimers. It can be proteolytically cleaved into a water soluble SC-like portion and a detergent soluble hydrophobic portion. Bovine SC is therefore most likely to be the extracellular part of an epithelial receptor which mediates the transport of IgA dimers to mucosal surfaces. The various tryptic fragments from bovine SC have been shown to differ in their relative binding affinities for IgM and IgA dimers. The results imply that the first three domains of bovine SC are most involved in binding and domains 4 and 5 play subsidiary roles. Computerized prediction and modelling methods have been used to deduce possible tertiary and quaternary structures for SC. There are good indications that the molecule has an elonaged "zig-zag" structure stabilized by longitudinal inter-domain contacts. A model of SC bound to IgA dimer is presented.

Amino Acid Sequence↗
PubMed1987

Tertiary structures for the extracellular domains of the epithelial polyimmunoglobulin receptor (secretory component) derived by primary structure comparisons with immunoglobulins.

The amino acid sequences of the rabbit receptor and human secretory component (SC) domains have been compared with those of immunoglobin (Ig) domains. Accessible and inaccessible sites of tryptic cleavage in bovine SC have been located by sequence homology. Computerized secondary structure prediction and three dimensional model building have been carried out. The resulting tertiary structures are extremely Ig-like consisting of two superposed beta-pleated sheets. All carbohydrate sites lie at external positions as do tryptic cleavage sites. Potential sites for tryptic hydrolysis that are not cleaved lie at buried or partially buried positions. 6. Inter-beta-sheet contact between domains appears to be highly unlikely so that the quaternary structure is largely determined by longitudinal contacts.

Amino Acid Sequence↗
PubMed1987

DNA sequence analysis of two bovine immunoglobulin CH gamma pseudogenes.

A bovine calf liver DNA library in lambda 2001 bacteriophage has been screened with a human Ig gamma 4 heavy-chain constant-region gene probe. Four hybridizing clones have been identified, and the DNA sequences in two of these, which have high homology with CH gamma genes, are reported here. Within the bovine sequences, four separate exons can be identified, corresponding to the three CH domains and the hinge of gamma heavy-chain genes. Both of these genes contain atypical sequences around one or more of their exon/intron boundaries with consequent loss of splice sites, indicating that these are probably gamma pseudogenes. One sequence codes for a C-terminal peptide which matches the 18-mer C-terminal heavy-chain peptide of bovine serum IgG2, the other encodes a C-terminal peptide unknown in the bovine. These results suggest that evolutionary duplication of CH gamma genes has occurred in the bovine.

Amino Acid Sequence↗
PubMed1986

A bovine epithelial membrane protein that binds polymeric immunoglobulin and has a structure related to that of bovine secretory component.

A protein of Mr 94000 was isolated from detergent-solubilized bovine intestinal, liver and mammary-gland membranes. It binds immunoglobulin M and also undergoes proteolytic fragmentation in a similar manner to bovine secretory component (Mr 74000). The affinity-purified membrane protein is therefore most likely to be the bovine epithelial receptor for polymeric immunoglobulin. A structural model is proposed.

Animals↗
PubMed1986

Unusual features of the T-cell receptor C domains are revealed by structural comparisons with other members of the immunoglobulin superfamily.

The amino acid sequences of the domains of human, mouse and rabbit T-cell antigen receptors have been aligned with those of immunoglobulin domains of known three-dimensional structure. Computerized secondary structure predictions have been performed on the sequences and putative models of the domains have been constructed. The receptor V alpha and V beta domains are closely related to immunoglobulin VH domains. The receptor C alpha domain shows some major divergences from immunoglobulin C domains and the C beta domain displays an unusual feature. The implications for T-cell receptor function are discussed.

Amino Acid Sequence↗
PubMed1985

Differences in fragmentation between bound and unbound bovine secretory component suggest a model for its interaction with polymeric immunoglobulin.

Unbound bovine secretory component was cleaved into two-domain and one-domain fragments by trypsin within 1 h. Bovine secretory component covalently bound to bovine IgA dimer, as in secretory IgA, was much more resistant to fragmentation, which did not proceed beyond the three-domain stage even after 5 h. Bovine secretory component non-covalently bound to bovine IgM or to human IgM or IgA polymer was also relatively resistant to fragmentation, which again was largely arrested at the three-domain stage. A model for the binding of secretory component to polymeric immunoglobulin is proposed.

Animals↗
PubMed1985

Glutathione transferases in primary rat hepatomas: the isolation of a form with GSH peroxidase activity.

A previously uncharacterized glutathione (GSH) transferase which is not apparent in normal liver, accounts for at least 25% of the soluble GSH transferase content of primary hepatomas induced by feeding N,N-dimethyl-4-aminoazobenzene. This enzyme is readily isolated, has an isoelectric point of 6.8, is composed of two identical subunits of apparent Mr 26000 and has GSH transferase activity towards a number of substrates including benzo(a)pyrene-7,8-diol-9,10-oxide. It is unusual in that it has GSH peroxidase activity towards fatty acid hydroperoxides but not towards the model substrates, cumene hydroperoxide and t-butyl hydroperoxide. It has been shown by tryptic peptide analysis to be distinct from GSH transferases composed of subunits 1, 2, 3, 4 or 6 and has been designated GSH transferase 7-7.

Animals↗
PubMed1985

Fragmentation and reduction of bovine secretory component. Preparation of a biologically active fragment and some evidence for a multiple-domain structure.

A tryptic fragment (A) of Mr 25000 was prepared from bovine secretory component. The fragment binds polymeric immunoglobulin, although 9 times less effectively than secretory component on a molar basis. The fragment has four buried half-cystine residues and two exposed half-cystine residues. It gives rise to two fragments of Mr 11000-13000 on prolonged digestion with trypsin, and these do not bind polymeric immunoglobulin. It is proposed that fragment A consists of two immunoglobulin-like domains. Bovine secretory component was found to have 9-11 buried half-cystine residues and four exposed half-cystine residues. Reduction and alkylation of the exposed residues decreases the binding of polymeric immunoglobulin by 3-fold. Initial tryptic cleavage of bovine secretory component gives a fragment (Q) disulphide-bridged to a further fragment (T). Fragment Q is similar in size to a three-domain immunoglobulin fragment, and fragment T is similar in size to a two-domain immunoglobulin fragment. The two-domain fragment A is derived from fragment Q by further tryptic cleavage. The results are compatible with the proposal by Mostov, Friedlander & Blobel [(1984) Nature (London) 308, 37-43] that secretory component consists of multiple immunoglobulin-like domains. The results also indicate that optimal binding of polymeric immunoglobulin involves several domains stabilized by an exposed disulphide bridge.

Alkylation↗