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A B Hooper

Publications and source records attributed to A B Hooper.

83 records · Page 5Linked to original sources
PubMed1973

Specific inhibitors of ammonia oxidation in Nitrosomonas.

The following compounds or treatments have been shown to inhibit the oxidation of ammonia, but not the oxidation of hydroxylamine in cells of Nitrosomonas: (i) metal-binding agents such as allylthiourea or potassium cyanide; (ii) compounds such as SKF 525 which interact with cytochrome P-450 of mammalian microsomes; (iii) carbon monoxide; (iv) inhibitors of catalase, peroxidase, and amine oxidases such as thiosemicarbazide, ethylxanthate, and iproniazid, respectively; (v) uncouplers of oxidative phosphorylation such as m-chlorocarbonylcyanidephenylhydrazone; (vi) electron acceptors such as phenazine methosulfate; (vii) compounds such as methanol or N(2)O which react with free radicals; and (viii) illumination with 420 lux (5,000 foot candles) of light.

Alcohols↗
PubMed1972

Electron transport systems of Nitrosomonas: isolation of a membrane-envelope fraction.

Freezing and thawing of Nitrosomonas, followed by centrifugation of the homogenate at 3,000 x g, resulted in a fraction which appeared to consist of an intact membrane-envelope complex and contained approximately 50% of the cell protein and more than 90% of the ubiquinone and cytochrome A-type mammalian cytochrome c oxidase activity. The supernatant fraction, resulting from subsequent centrifugation of the extract at 100,000 x g, contained approximately 50% of the cell protein and more than 80% of the B- and C-type cytochrome and P-463 and the enzymes glutamate dehydrogenase; hydroxylamine dehydrogenase; nitrite synthetase; nitrite reductase; and 2,6-dichlorophenolindophenol-, p-phenylenediamine-, pyrogallol-, and hydroquinone-oxidase. Data on the concentration of electron transport components in Nitrosomonas are presented.

Bacterial Proteins↗
PubMed1970

Polyphosphate and orthophosphate content of Nitrosomonas europaea as a function of growth.

After inoculation of a stationary-phase culture of Nitrosomonas europaea into fresh growth solution, the cell-associated orthophosphate increased rapidly to 800 mumoles/g (wet weight), whereas the acid-insoluble long-chain polyphosphate content decreased rapidly to 22 mumoles/g. As growth proceeded, the orthophosphate content decreased rapidly to a level of 15 mumoles/g and the long-chain polyphosphate content gradually increased to 60 to 90 mumoles/g. When the pH of a culture of Nitrosomonas decreased during growth below approximately 7.4, the rate of nitrite and polyphosphate synthesis increased and the ratio of change in protein to change in nitrite decreased. When the pH of the culture was maintained above 7.6 throughout growth, polyphosphate accumulation, an increased rate of nitrite and polyphosphate synthesis, and a decreased ratio of change in protein to change in nitrite were not observed. Cells of Nitrosomonas apparently accumulated polyphosphate when adenosine triphosphate generated during the oxidation of ammonia to nitrite was not efficiently used to promote an increase in cell mass. The rapid hydrolysis of polyphosphate after the transfer of stationary-phase cells into fresh growth solution was found to be triggered primarily by the higher pH of the fresh growth solution. The efflux of orthophosphate during culture growth was not associated with a decrease in the pH of the growth solution. Data on the chemical composition of Nitrosomonas are presented.

Adenosine Triphosphate↗
PubMed1969

Biochemical basis of obligate autotrophy in Nitrosomonas europaea.

The specific activities of isocitric dehydrogenase, alpha-ketoglutaric dehydrogenase, succinic dehydrogenase, malic dehydrogenase, and reduced nicotinamide adenine dinucleotide (NADH) oxidase were determined in extracts of Nitrosomonas europaea and compared with the corresponding values for Anacystis nidulans and autotrophically grown Hydrogenomonas eutropha. In common with other obligate autotrophs and in contrast to facultative autotrophs, Nitrosomonas extracts lacked alpha-ketoglutaric dehydrogenase and KCN-sensitive NADH oxidase activity and had low succinic dehydrogenase activity. The Nitrosomonas NADH oxidase appeared to be of the peroxidase type.

Isocitrate Dehydrogenase↗