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S A Lister

Publications and source records attributed to S A Lister.

At least 19 recordsLinked to original sources
PubMed1996

E144S active-site mutant of the Bacillus cereus thermolysin-like neutral protease at 2.8 A resolution.

The X-ray crystal structure of the Bacillus cereus neutral protease (CNP) active-site mutant E144S, in which the putative general base proposed for the thermolysin-like zinc neutral proteases, Glu144, has been replaced by serine, has been determined to a resolution of 2.8 A. This represents the first crystal structure of an active-site mutant of a zinc neutral protease. The E 144S mutant was crystallized in the hexagonal space group, P6(5)22, with unit-cell dimensions a = b = 76.57, c = 201.91 A. Although the ligands involved in zinc coordination in the active site are identical to those found in the wild-type protein, the mutation results in a modified environment around the zinc ion; particularly with respect to the water molecules. While the structure of the mutant is similar to that of wild type, its protease activity is reduced to 0.16% that of the wild-type CNP and the protein is virtually resistant to autolysis in the presence of calcium. The lowered protease activity of the mutant is consistent with the role proposed for Glu144 as the general base in the catalysis of thermolysin-like neutral proteases [Matthews (1988). Acc. Chem. Res. 21, 333-340]. We suggest that the residual activity of the E144S mutant arises from a water molecule, which is found within hydrogen-bonding distance of Ser144, acting as a general base in the catalytic function of the mutant.

Journal Article↗
PubMed1989

An outbreak of disease due to chicken anaemia agent in broiler chickens in England.

Outbreaks of clinical chicken anaemia in four broiler chicken flocks affected chicks which were all the progeny of the same parent flock. Three of the flocks were reared on farms in the south-east of England and in these flocks clinical disease did not occur in other chicks of the same age. The fourth flock was reared in a positive-pressure isolator and clinical disease appeared at 10 days of age. Chicken anaemia agent was isolated from three of the flocks. The clinical signs, post mortem lesions and histopathological changes were similar to those reported in outbreaks of the disease in other countries. The parent flock seroconverted to chicken anaemia agent, as determined by fluorescent antibody tests, during the course of the outbreaks.

Anemia↗
PubMed1989

[Comparative studies of paramyxovirus isolates from wild birds].

As a result of a surveillance programme in North-Germany, paramyxovirus-isolates of serogroup 1 with different pathogenicity were isolated from different species of feral birds (Black-headed gull, mallard, tawny owl, tree sparrow, mute swan). In chick embryo fibroblast monolayers these isolates produced plaques exhibiting different plaque morphology. After cloning the isolates, further physicochemical, serological and pathogenicity testings were performed. On the basis of mean death time and intracerebral pathogenicity index, two of the isolates were found to be avirulent (lentogenic), whereas the others proved to be virulent (velogenic). SDS-Polyacrylamide-gel-electrophoresis showed polypeptide patterns similar to that of the PMV-1 reference strains. Summarizing all relevant findings of these investigations under consideration of the suggestions for the virological description of avian PMV (Alexander, 1987; Alexander et al., 1987; Who-Expert-Committee, 1980), including the recently established serotyping by means of monoclonal antibodies, the following designations of the PMV isolates tested herein are proposed: 1. PMV-1/black-headed gull/Germany/SSP-233/83, lentogenic NDV, monoclonal antibody group G 2. PMV-1/mallard/Germany/SSP-284/83, lentogenic NDV, monoclonal antibody group H 3. PMV-1/tawny owl/Germany/SSP-262/84, velogenic NDV, monoclonal antibody group B 4. PMV-1/tree sparrow nestling/Germany/SSP-352/84, velogenic NDV, monoclonal antibody group B 5. PMV-1/mute swan/Germany/SSP-204/85, velogenic NDV, monoclonal antibody group B.

Animals↗
PubMed1987

Retarded growth rate and delayed onset of egg production associated with spirochaete infection in pullets.

Retarded growth rates and delayed onset of egg production were recorded in 22-week-old pullets reared on deep litter and with indirect contact with pigs. Birds reared in cages or transferred to cages were unaffected. Spirochaetes were isolated and identified from the intestines of the pullets reared on deep litter but not from those reared in cages. Birds kept solely on deep litter were more severely affected, with 24 per cent immature birds and 10 per cent mortality compared with those transferred from deep litter to cages where no mortality was recorded but 15 to 22 per cent were found to be immature. The histopathological changes are described and the significance of the findings is discussed.

Animals↗