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Biomedical subjects

L L Barton

Publications and source records attributed to L L Barton.

11 recordsLinked to original sources
PubMed1979

Oxidative phosphorylation linked to the dissimilatory reduction of elemental sulphur by Desulfovibrio.

Hydrogenase and cytochrome c3 purified from Desulfovibrio gigas and D. desulfuricans strain Norway form a soluble complex which is capable of transferring electrons from molecular hydrogen to colloidal sulphur (S0). In this reaction, sulphur is reduced to hydrogen sulphide. Since both strains are capable of growth using elemental sulphur as terminal electron acceptor, it was of interest to check for oxidative phosphorylation in this sulphur reduction sytem. Membranes isolated from D. gigas or D. desulfuricans strain Norway contain hydrogenase and c-type cytochromes and catalyse the H2 leads to S0 reaction. With D. gigas, esterification of orthophosphate is coupled to the membrane-mediated transfer of electrons from H2 to S0. A P/2e ratio of 0.1 was observed and this value could be reduced by the addition of colloidal sulphur with c2 may be more than a purely chemical reaction. Since whole cells can use sulphur flower while cell-free extracts react only with colloidal sulphur, it is evident that cells handle sulphur in a way which is not yet fully understood.

Adenosine Triphosphate↗
PubMed1978

Energy-driven uptake of humic acids by Aspergillus niger.

The uptake of humic acids by mycelia of Aspergillus niger was demonstrated to be energy-dependent with a sensitivity to sodium azide and to 2,4-dinitrophenol. Greater uptake of humic acids by submerged mycelium occurred at pH 3.0 and at 32 degrees C. The rate of uptake was influenced by the concentration of humic acids with an apparent Km of 0.2 grams/ml and with a Vmax of 0.13 mg humic acids per gram mycelial dry weight.10 min-1. In the absence of added energy source, Vmax of 0.05 mg humic acids per gram mycelial dry wt.10 min-1 was obtained; however, the affinity for humic acids by this uptake system was the same as for the energy-driven process. Apparent binding of humic acids to cell structures was indicated because only 41.8% of the humic acids taken up by the energy-dependent system could be recovered.

Aspergillus niger↗
PubMed1977

Evidence for the presence of phosphoriboisomerase and ribulose-1,5-diphosphate carboxylase in extracts of Desulfovibrio vulgaris.

Cell extracts of Desulfovibrio vulgaris were found to incorporate 14CO2 into acid-stable products when ribose-5-phosphate or ribulose-1,5-diphosphate was used as a substrate. This CO2 fixation required adenosine triphosphate and produced 3-phosphoglyceric acid as one of the products. The assimilation of CO2 by pentose phosphates was unrelated to the pyruvate-CO2 exchange reaction. The pyruvate-CO2 exchange did not require adenosine triphosphate, did not produce phosphorylated compounds, and, unlike the pentose phosphate system, required an acidic protein fraction for activity.

Adenosine Triphosphate↗
PubMed1977

Nicotinamide adenine dinucleotide -- independent formate dehydrogenase in Mycobacterium phlei.

Formate dehydrogenase activity (EC 1.2.1.2) has been demonstrated in cell-free preparations of Mycobacterium phlei by following the reduction of 2,6 dichlorophenolindophenol. thiazolyl blue tetrazolium, or equine cytochrome c. The reduction of equine cytochrome c was inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide. Neither nicotinamide adenine dinucleotide nor nicotinamide adenine dinucleotide phosphate were reduced by this formate dehydrogenase. The enzyme was constitutive and associated with the particular fraction. The greatest level of activity was observed at pH 9.0, with 8 mM formate, and with extracts of cells taken from the log phase of growth. Formaldehyde, hypophosphite, nitrate, and bicarbonate all inhibited the oxidation of formate.

2,6-Dichloroindophenol↗
PubMed1975

Hyperbilirubinaemia and bacterial infection in the newborn. A prospective study.

The incidence of bacterial infection associated with unexplained hyperbilirubinaemia was determined prospectively in 69 infants under 2 weeks of age. Blood and urine cultures were obtained from all patients, and 22 patients had their CSF cultured. Bacterial infection was documented in only 2 infants, who had asymptomatic Gram-negative urinary tract infection.

Ampicillin↗