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Biomedical subjects

M G Burdon

Publications and source records attributed to M G Burdon.

14 recordsLinked to original sources
PubMed1991

Isolation and detection of urease genes in Ureaplasma urealyticum.

Urease from ureaplasmas was purified by immunoaffinity chromatography, and the N-terminal amino acid sequence was determined for two of the three subunits. These sequences were used to design primers for a polymerase chain reaction (PCR) that amplified most of the gene coding for one of the subunits. By using a novel "PCR walking" technique, we synthesized almost the complete locus on two overlapping PCR products. We present here a partial nucleotide sequence of the urease locus from Ureaplasma urealyticum (serotype 8), which agrees with our N-terminal amino acid data but differs slightly from the sequence previously reported (A. Blanchard, Mol. Microbiol. 4:669-676, 1990). Also described are PCR primers, intended for diagnostic use, that amplify a sequence from all Ureaplasma strains tested but not from any other mycoplasmas or urease-positive bacteria.

Amino Acid Sequence↗
PubMed1989

The urease of Ureaplasma urealyticum.

The urease from Ureaplasma urealyticum (serotype 8) has been purified by immuno-affinity column chromatography. Two active nickel-containing forms of the enzyme were demonstrated by non-denaturing electrophoretic analysis and a single active peak of apparent molecular mass 190 kDa was shown by FPLC. Total inactivation and denaturation of the enzyme to give three subunit polypeptides (one of 72 kDa containing nickel, one of 14 kDa and one of 11 kDa) was achieved by treatment with SDS and boiling. Densitometry suggested that the active enzyme contains equimolar ratios of the three subunits and hence is a hexamer. The enzyme displayed a pH optimum of 6.9 and pI values were determined. Storage of the purified enzyme at -70 degrees C followed by thawing to 20 degrees C caused a partial breakdown to inactive subunits. Anti-urease monoclonal antibodies bound both to the active enzyme and to the inactive 72 kDa subunit, and the antibodies cross-reacted with ureases from all of the other human serotypes. Competition assays with the antibodies revealed four distinct epitopes of the enzyme, all distinct from its active site.

Antibodies, Monoclonal↗
PubMed1988

An antigenic analysis of the adenovirus type 2 fibre polypeptide.

Twenty-seven monoclonal antisera were generated against the SDS-denatured fibre of adenovirus type 2. The antisera were characterized using radioimmune assay, fluorescent antibody tests, immune precipitation, Western blotting, haemagglutination and neutralization, and formed six groups as follows: A, type-specific neutralizing antisera which exhibited haemagglutination inhibition (Hi+); B, type-specific non-neutralizing antisera which did not exhibit haemagglutination inhibition (Hi-); C, subgroup-specific neutralizing antisera Hi+; D, a subgroup-specific neutralizing antiserum Hi-; E, subgroup-specific non-neutralizing antisera Hi-; F, a subgroup-specific neutralizing antiserum Hi- which did not react in Western blotting tests. The C-terminal 201 amino acids of the fibre were expressed in Escherichia coli and a total of six antisera from groups A, B and C recognized five epitopes carried on this region which in several models is thought to form the knob of the fibre. At least eight epitopes were expressed by the entire native fibre. The five epitopes of the C-terminal end of the fibre formed three antigenic sites. Two sites each consisted of a neutralizing type-specific and a neutralizing group-specific epitope which overlapped in position. The remaining site consisted of a type-specific, non-neutralizing epitope.

Adenoviridae↗
PubMed1985

Double-strand cleavage at a two-base deletion mismatch in a DNA heteroduplex by nuclease S1.

A two-base deletion mismatch was generated in a DNA heteroduplex by hybridization of two linear plasmid DNA molecules differing only by the presence of a two-base deletion in one of them. The heteroduplex was shown to be sensitive to double-strand cleavage by nuclease S1, thus demonstrating the potential value of single-stranded probes for the detection of polymorphisms in genomic DNA due to very small deletions.

Base Sequence↗
PubMed1980

Normal subunit cleavage of alpha-2-macroglobulin in cystic fibrosis.

Alpha-2-macroglobulin (alpha 2-M) has been purified from the plasma of patients with cystic fibrosis and normal controls, and the proteolytic subunit cleavage on reaction with trypsin has been compared. As no differences were observed between the two groups, a primary genetic defect affecting alpha 2M subunit cleavage in cystic fibrosis is unlikely.

Adolescent↗
PubMed1980

The agglutination of Proteus vulgaris by cystic fibrosis serum: a re-examination.

The agglutination of the bacterium Proteus vulgaris by serum from cystic fibrosis patients and obligate heterozygotes was shown to be insufficiently specific or reproducible to be of diagnostic value by itself. Approximately 20% of health controls gave a substantial agglutination reaction, whereas the carrier frequency for cystic fibrosis is around 5%. The agglutination did not predominantly involve the bacterial flagella, but appeared to depend on components of the cell surface. The main serum proteins that bind to P. vulgaris cells were shown to be albumin, immunoglobulin G, and complement component C3. In addition, an unidentified protein(s) of low molecular weight was found to bind to the cells. However, no systematic differences were found in the proteins that bind to P. vulgaris cells between cystic fibrosis and normal sera.

Agglutination↗
PubMed1966

The purification from rat liver of a nuclease hydrolysing ribonucleic acid and deoxyribonucleic acid.

1. The purification of a nuclease from rat-liver mitochondria is described. The mitochondria are rendered soluble by treatment with Triton X-100 and, after fractionation with ammonium sulphate and acetone, the active fraction is further purified by chromatography on DEAE-cellulose and Sephadex G-75 to give a purification of over 700-fold. 2. The purified enzyme was only very slightly contaminated with deoxyribonuclease II, phosphodiesterase and phosphomonoesterase. The individual activities of these enzymes did not exceed 0.1% of the activity of the liver nuclease. 3. The purified enzyme attacked RNA more rapidly than denatured DNA and hydrolysed native DNA more slowly than denatured DNA. 4. There is some evidence to suggest that the nucleolytic activity of the purified preparation towards native DNA, denatured DNA and RNA is associated with a single protein. 5. The enzyme is relatively labile but is stabilized in the presence of 20% (w/v) glycerol or 10mm-2-mercaptoethanol.

Animals↗