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D E Mahony

Publications and source records attributed to D E Mahony.

50 records · Page 3Linked to original sources
PubMed1975

Lyophilized 7 alpha-hydroxysteroid dehydrogenase: a stable enzyme preparation for routine bile acid analysis.

Preparations of 7 alpha-hydroxysteroid dehydrogenase (7 alpha-HSDH) from Escherichia coli strain 23 can be frozen and thawed without significant loss of activity. 7 alpha-HSDH may then be lyophilized into powder form, which is stable for more than 6 months (3% loss of activity). The lyophilized 7 alpha-HSDH preparation has the additional advantage over previously described preparations of a low and stable fluorescence background when applied to the fluorometric estimation of bile acids, especially in combination with thin-layer chromatography. Analysis of duodenal aspirates from 18 normal subjects gave bile acid ratios identical with those reported earlier and obtained by using gas-liquid chromatography. A significant difference in the glycine: taurine ratio between males and females was observed.

Bile Acids and Salts↗
PubMed1974

Bacteriocin susceptibility of Clostridium perfringens: a provisional typing schema.

Ninety-four strains of Clostridium perfringens were examined for bacteriocin production. Bacteriocins produced by ten of these strains were selected for typing 274 cultures of C. perfringens. The bacteriocins were prepared by growing the producer strains in broth and precipitating the active principle from the supernatant fluids of centrifuged cultures with ammonium sulfate. All bacteriocins were titrated against a common indicator strain, adjusted to equivalent titers, and spotted onto blood agar plates seeded with the test organisms. Fifty different bacteriocin sensitivity patterns were observed. These patterns were organized into seven groups bearing some relationship, and the largest number of strains falling into any one pattern did not exceed 16% of the total strains tested. Ninety-nine percent of all isolates were typable. The new method should prove useful in studies where strains must be fingerprinted.

Bacteriocins↗
PubMedDate not supplied

12alpha- and 7alpha-hydroxysteroid dehydrogenase activities from Fusobacterium spp.

On screening fecal organisms for hydroxysteroid dehydrogenase activities applicable to bile acid metabolism studies, we have isolated a gram negative "Bacteroides-like" anaerobe which yields both 12alpha- and 7alpha-hydroxysteroid dehydrogenase (HSDH) activities in cell-free preparation. At the optimal harvest time of 36 hours, approximately 4500 units 12alpha-HSDH and 360 units 7alpha-HSDH were produced per 10(10) viable cells. The two enzymes appear to be separate entities in the basis of their stabilities on freezing, and prolonged storage at room temperature and elution volumes on Sephadex G 200. Thin layer chromatography studies on oxidation products confirmed the respective sites of oxidation to be the 12alpha-OH and 7alpha-OH position. No 3alpha-OH oriented activity was measurable. Preliminary kinetic studies of the 12alpha-HSDH revealed a broad pH curve with optimal activity at pH 9.5. Michaelis constants for glycodeoxycholate and NADP were estimated at 1.5 x 10(-4)M and 3.3 x 10(-5)M respectively.

Animals↗