Biomedical subjects

G Fuchs

Publications and source records attributed to G Fuchs.

At least 163 records · Page 9Linked to original sources

PubMed1975

The active species of 'CO2' utilized by reduced ferredoxin:CO2 oxidoreductase from Clostridium pasteurianum.

Reduced ferredoxin:CO2 oxidoreductase (CO2 reductase) from Clostridium pasteurianum catalyzes the reduction of 'CO2' to formate with reduced ferredoxin, an isotopic exchange between 'CO2' and formate in the absence of ferredoxin, and the oxidation of formate to 'CO2' with oxidized ferredoxin. The active species of 'CO2', i.e. CO2 or HCO3 (H2CO3), utilized by the enzyme was determined. The method employed for the species identification was that of Copper et al. (1968). Both 'CO2' reduction to formate and the exchange reaction were studied. Data were obtained which are compatible with those expected if CO2 is the active species. The V and the dissociation constant Ks of the enzyme - CO2 complex in dependence of pH were determined from initial velocity studies of the exchange reaction. V was found to be only slightly affected by pH between 5.5 and 7.5. Ks was markedly dependent on pH; the constant increased with decreasing pH from 0.2 mM at pH 7.5 to 3 mM at pH 5.5.

Aldehyde Oxidoreductases↗

PubMed1975

[Breast cancer in women as a paradigm for ageing as a hidden syncarcinogenic factor].

In man the application of so-called cancerogenic factors and the latency period of a neoplasm until its manifestation includes the factor of biological ageing. There are in humans relationships between age, localisation and incidence of tumour which can retrospectively appear as syncarcinogenic factors. Using breast carcinoma in women as an example, it is shown that a carcinogenic effect cannot be demonstrated for two of the supposed carcinogenic factors, namely repeated diagnostic radiographic measures and administration of Rauwolfia-alkaloid containing drugs.

Age Factors↗

PubMed1975

Reduced ferredoxin: CO2 oxidoreductase from Clostridium pasteurianum. Effect of ligands to transition metals on the activity and the stability of the enzyme.

Reduced ferredoxin: CO2 oxidoreductase (CO2-reductase) from Clostridium pasteurianum catalyzes the reduction of CO2 to formate at the expense of reduced ferredoxin, an isotopic exchange between CO2 and formate in the absence of ferredoxin, and the oxidation of formate to CO2 with oxidized ferredoxin. The three activities were found to be equally affected by monovalent anions known to be ligands to transition metals: The enzyme was reversibly inhibited by azide (Ki = 0.004mM), cyanate (Ki = 0.3 mM), thiocyanate (Ki = 1mM), nitrite (Ki = 0.4mM), nitrate (Ki = 6mM), chlorate (Ki = 3mM), fluoride (Ki = 5mM), and by chloride, bromide, iodide (Ki greater than 5mM). There was no observable effect of pH on the inhibition constants. The enzyme was not inhibited by carbon monoxide. The enzyme was irreversibly inactivated by low concentrations (10muM) of cyanide. The rate of inactivation increased with increasing pH with an inflection point near pH 9.5. Reduced ferredoxin and formate rather than oxidized ferredoxin or CO2 protected the enzyme from inactivation by cyanide. The enzyme was protected by azide and cyanate from inactivation. In the presence of high concentrations of the monovalent anions the rate of inactivation by heat (55 degrees C), by molecular oxygen, and by cyanide was decreased by a factor of more than 100. Half maximal protection was observed at the Ki concentrations of the two reversible inhibitors. The data are interpreted to indicate that a transition metal of weak "a class" character and a disulfide are catalytically significant groups of CO2-reductase from C. pasteurianum.

Anions↗

PubMed1975

Influence of sugar content in soft bread on pH of human dental plaque.

Quantitative determination of monosaccharides, disaccharides and sorbitol by use of gas-liquid chromatography (GLC) was performed on thirty-three samples of different commercial soft bread. Maltose was found in all the bread samples. Fructose and glucose were found only in samples of sweetened bread. Sucrose was detected in 5 samples, lactose in 2, and sorbitol in 2. Up to 20 per cent of the fresh bread weight was found to be low-molecular weight carbohydrates. Plaque pH-changes were studied in 18 persons following a 30-second month rinse with each of 3 solutions: (1) 50% sucrose, (2) water extract of sweetened bread, and (3) water extract of unsweetened bread. Mouth rinsing with the extract of sweetened wheat bread (sucrose 7.7 per cent of the dough weight) caused pH-decreases in plaque which were significantly more pronounced than those induced by the water extract of unsweetened wheat bread.

Adolescent↗

PubMed1975