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P Fletcher

Publications and source records attributed to P Fletcher.

At least 91 records · Page 5Linked to original sources
PubMed1981

Evolutionary relationships among gamma-carboxymuconolactone decarboxylases.

gamma-Carboxymuconolactone decarboxylase (EC 4.1.1.44) from Azotobacter vinelandii resembled the isofunctional enzymes from Acinetobacter calcoaceticus and Pseudomonas putida. All three decarboxylases appeared to be hexamers formed by association of identical subunits of about 13,300 daltons. The A. vinelandii and P. putida decarboxylases cross-reacted immunologically with each other, and the NH2-terminal amino acid sequences of the enzymes differed in no more than 7 of the first 36 residues. In contrast, the A. calcoaceticus decarboxylase did not cross-react with the decarboxylase from A. vinelandii or P. putida; the NH2-terminal amino acid sequences of these enzymes diverged about 50% from the NH2-terminal amino acid sequence of the A. calcoaceticus decarboxylase.

Acinetobacter↗
PubMed1980

Work for minds on the mend.

People suffering from mental illness need the opportunity to regain their self-esteem and find an identity. 'Restore', a pioneer scheme in Oxford, provides a new approach to the provision of sheltered work for the mentally ill. Here Paul Fletcher describes how the scheme has brought a new dimension to the psychiatric services.

England↗
PubMed1980

Repetitions in the NH2-terminal amino acid sequence of beta-ketoadipate enol-lactone hydrolase from Pseudomonas putida.

Muconolactone delta-isomerase (EC 5.3.3.4) and beta-ketoadipate enol-lactone hydrolase (EC 3.1.1.24) mediate consecutive reactions in the beta-ketoadipate pathway of bacteria. An earlier investigation (Yeh, W.K., Davis, G., Fletcher, P., and Ornston, L.N. (1978) J. Biol. Chem. 253, 4920-4923) revealed that the respective NH2-terminal amino acid sequences of Pseudomonas putida muconolactone isomerase and Acinetobacter calcoaceticus beta-ketoadipate enol-lactone hydrolase II are evolutionarily homologous. In this report, we describe the purification of Pseudomonas beta-ketoadipate enol-lactone hydrolase and present evidence indicating that the protein is a trimer composed of identical 11,000-dalton subunits. The NH2-terminal amino acid sequences of Pseudomonas muconolactone isomerase and Pseudomonas enol-lactone hydrolase have diverged widely from each other, yet the two sequences contain different fragments of an ancestral sequence which is represented in Acinetobacter enol-lactone hydrolase II. The widely divergent Pseudomonas muconolactone isomerase and Pseudomonas enol-lactone hydrolase sequences each contain unique sets of repeated peptides. In principle, the repetitive sequences might have been introduced by elongation mutations which occurred early in the evolution of the proteins. However, the divergence of Pseudomonas muconolactone isomerase and Pseudomonas enol-lactone hydrolase is so extreme that the observed sequence repetitions cannot have been conserved from ancestral duplication mutations. Rather, the data favor the interpretation that copies of DNA were substituted into structural genes for the enzymes as they diverged.

Adipates↗
PubMed1980

Evolutionary divergence of co-selected beta-ketoadipate enol-lactone hydrolases in Acinetobacter calcoaceticus.

Muconolactone isomerase (EC 5.3.3.4) and beta-ketoadipate enol-lactone hydrolase (EC 3.1.1.24) mediate consecutive catabolic steps in bacteria. Separately inducible beta-ketoadipate enol-lactone hydrolases I and II are formed in representatives of Acinetobacter calcoaceticus. When subjected to DEAE-cellulose chromatography, Acinetobacter enol-lactone hydrolase I displays heterogeneous behavior which, in whole or in part, appears to be due to modifications of sulfhydryl groups in the protein; the enzyme is unusual in that its NH2-terminal amino acid is cysteine. Comparison of the NH2-terminal amino acid sequence of Acinetobacter enollactone hydrolase I, reported here, with the corresponding amino acid sequences of Acinetobacter enollactone hydrolase II and Pseudomonas enol-lactone hydrolase indicates that all three proteins have diverged widely from a common evolutionary origin. Sequence comparisons suggest that divergence of the Acinetobacter enol-lactone hydrolase structural genes was achieved by substitution with DNA derived from an ancestral muconolactone isomerase structural gene.

Acinetobacter↗
PubMed1980

Homologies in the NH2-terminal amino acid sequences of gamma-carboxymuconolactone decarboxylases and muconolactone isomerases.

gamma-Carboxymuconolactone decarobxylase (EC 4.1.1.44) and muconolactone isomerase (EC 5.3.3.4) mediate chemically analogous reactions in bacteria. The enzymes are inducible, and different metabolites trigger the respective syntheses of the decarboxylases in Acinetobacter calcoaceticus and Pseudomonas putida. The decarobxylases share similar oligomeric structures in which identical subunits of about 13,300 daltons appear to be self-associated into hexamers. Identical residues are found in 18 of the first 36 positions of the enzymes' NH2-terminal amino acid sequences. Thus, genetic rearrangements appear to have placed homologous structural genes for the decarboxylases under different transcriptional control in the two bacterial species. The NH2-terminal amino acid sequences of the decarboxylases and muconolactone isomerases are similar, suggesting that a common ancestral protein gave rise to the enzymes with different (albeit analogous) activities. In addition, the NH2-terminal amino acid sequences of the decarboxylases appear to have been conserved at a second region within the primary structure of the muconolactone isomerases. As has been observed with the two enol-lactone hydrolases (EC 3.1.3.24) of Acinetobacter, the structural genes for the decarboxylases and the isomerases appear to have diverged widely as they were co-selected within a single cell line, In part the divergence appears to have been achieved by mutations in which fragments of DNA within structural genes are replaced with fragments of DNA derived from a co-evolving sequence.

Acinetobacter↗
PubMed1979

Vertebrate lectins, Comparison of properties of beta-galactoside-binding lectins from tissues of calf and chicken.

Beta-galactoside-binding lectins were isolated from various calf tissues and from chicken hearts by affinity chromatography on asialofetuin-Sepharose, and were compared with respect to biochemical characteristics, binding properties, antigenic cross-reactivity, and cellular localization. The lectins are all thiol group-requiring, divalent cation-independent dimers, of apparent monomer mol wt 12,000 (calf lectins) or 13,000 (chicken lectin), and acidic pI. The calf lectins appear essentially identical by dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing, amino acid composition, and radioimmunoassay, while the chicken lectin is distinctly different by these criteria. However, all of the lectins competed for the same binding sites on rabbit erythrocytes, and could be inhibited by the same saccharide haptens (notably lactose and thiodigalactoside). Immuno-fluorescence studies on several cultured cell lines revealed that the bovine and chicken lectins had primarily an intracellular cytoplasmic localization. The beta-galactoside-binding lectins of vertebrates appear to be species-specific rather than tissue-specific.

Amino Acids↗
PubMed1979

The pathology of intrarenal vascular lesions associated with the loin-pain-haematuria syndrome.

The histological appearances of the proximal and peripheral intrarenal arteries and renal cortex have been examined in 3 patients who underwent nephrectomy for intractable pain associated with the loin-pain-haematuria syndrome. Marked 'atherosclerotic' changes were noted to involve segmental, lobar, interlobar and arcuate arteries with evidence in one kidney of early microaneurysmal formation. These lesions of the more proximal intrarenal arteries were associated with occlusive lesions of the interlobular arteries, areas of cortical ischaemia and cortical infarcts consistent with the changes resulting from microemboli. The histological appearances correlated well with previously described angiographic findings.

Adult↗
PubMed1978

Continuing education.

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Education, Nursing, Continuing↗