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J R Quayle

Publications and source records attributed to J R Quayle.

50 records · Page 3Linked to original sources
PubMed1968

Choice between autotrophy and heterotrophy in Pseudomonas oxalaticus. Utilization of oxalate by cells after adaptation from growth on formate to growth on oxalate.

1. The labelling patterns of phosphoglycerate obtained from formate-grown or oxalate-grown Pseudomonas oxalaticus after exposure for 15sec. to [(14)C]formate or [(14)C]oxalate respectively were determined. 2. The phosphoglycerate obtained from the formate-grown cells contained 78% of the radioactivity in the carboxyl group. This is in accord with that predicted for operation of the ribulose diphosphate cycle of carbon dioxide fixation. 3. The labelling pattern of the phosphoglycerate obtained from the oxalate-grown cells approached uniformity, as predicted for the heterotrophic pathway of oxalate assimilation. The departure from complete uniformity may have been due to concurrent (14)CO(2) fixation into C(4) dicarboxylic acids. 4. The labelling pattern of phosphoglycerate obtained from cells that had just started to grow on oxalate after adaptation from formate was determined after incubation of the cells for 15sec. with [(14)C]oxalate. This pattern approached uniformity. 5. The pathway of incorporation of (14)CO(2) into cells that had just started to grow on oxalate after adaptation from formate, in the presence of either formate or oxalate as energy source, was studied by chromatographic and radio-autographic analysis. 6. It is concluded from the isotopic data that a mixed heterotrophic-autotrophic metabolism, with the former mode predominating, operates in the initial stages of growth on oxalate after adaptation from growth on formate.

Journal Article↗
PubMed1968

Choice between autotrophy and heterotrophy in Pseudomonas oxalaticus. Growth in mixed substrates.

1. The type of metabolism adopted by Pseudomonas oxalaticus during growth on a variety of carbon sources was studied. 2. The only substrate upon which autotrophic growth was observed is formate. 3. In mixtures of formate and those substrates upon which the organism can grow faster than on formate, e.g. succinate, lactate or citrate, heterotrophic metabolism results. 4. In mixtures of formate and those substrates upon which the organism can grow at a similar rate to that on formate, e.g. glycollate or glyoxylate, the predominant mode of metabolism adopted is heterotrophic utilization of the C(2) substrate coupled with oxidation of formate as ancillary energy source. 5. P. oxalaticus grows on oxalate 30% slower than on formate. In mixtures of formate and oxalate, the predominant mode of metabolism adopted is autotrophic utilization of formate coupled with oxidation of oxalate as ancillary energy source. 6. In mixtures of formate and those substrates upon which the organism grows at a much lower rate than on formate, e.g. glycerol and malonate, the predominant mode of metabolism adopted is autotrophic utilization of formate. 7. It is concluded that synthesis of the enzymes involved in autotrophic metabolism is controlled by a combination of induction and metabolite repression.

Journal Article↗
PubMed1967

Microbial growth on C1 compounds. Uptake of [14C]formaldehyde and [14C]formate by methane-grown Pseudomonas methanica and determination of the hexose labelling pattern after brief incubation with [14C]methanol.

1. A study has been made of the incorporation of carbon from [(14)C]formaldehyde and [(14)C]formate by cultures of Pseudomonas methanica growing on methane. 2. The distribution of radioactivity within the non-volatile constituents of the ethanol-soluble fractions of the cells, after incubation with labelled compounds for periods of up to 1min., has been analysed by chromatography and radioautography. 3. Radioactivity was fixed from [(14)C]formaldehyde mainly into the phosphates of the sugars, glucose, fructose, sedoheptulose and allulose. 4. Very little radioactivity was fixed from [(14)C]formate; after 1min. the only products identified were serine and malate. 5. The distribution of radioactivity within the carbon skeleton of glucose, obtained from short-term incubations with [(14)C]methanol of Pseudomonas methanica growing on methane, has been investigated. At the earliest time of sampling over 70% of the radioactivity was located in C-1; as the time increased the radioactivity spread throughout the molecule. 6. The results have been interpreted in terms of a variant of the pentose phosphate cycle, involving the condensation of formaldehyde with C-1 of ribose 5-phosphate to give allulose phosphate.

Carbon Isotopes↗
PubMed1967

The synergistic decarboxylation of glyoxylate and 2-oxoglutarate by an enzyme system from pig-liver mitochondria.

1. An enzyme system that catalyses a synergistic decarboxylation of glyoxylate and 2-oxoglutarate has been purified from pig-liver mitochondria. 2. The purified system is specific for glyoxylate and 2-oxoglutarate as substrates, although in earlier stages of purification glycine and l-glutamate are also active. 3. The reaction is inhibited strongly by EDTA and N-ethylmaleimide. Substrate analogues, present at concentrations equimolar with respect to the substrates, are not effective as inhibitors. 4. The reaction proceeds in the absence of added cofactors. Magnesium chloride, mercaptoethanol and sucrose stimulate the reaction, and stabilize the activity of the enzyme. 5. The pH optimum of the reaction is 7.0. The K(m) values of glyoxylate and 2-oxoglutarate, at saturating concentration of the corresponding co-substrate, are 16mm and 3.6mm respectively. 6. Isotopic work with specifically labelled [(14)C]glyoxylate and 2-oxo[(14)C]-glutarate suggests that the enzyme system catalyses an initial condensation of glyoxylate and 2-oxoglutarate that results in, or leads to, release of C-1 of both substrates as carbon dioxide. C-2 of glyoxylate and C-5 of 2-oxoglutarate do not appear as carbon dioxide. 7. The stoicheiometry of the reaction is complex. During the initial stages of the reaction, more carbon dioxide is recovered from 2-oxoglutarate than from glyoxylate. Subsequently, there is a disproportionate increase with time of carbon dioxide evolution from the carboxyl group of glyoxylate. The excess of decarboxylation of glyoxylate over 2-oxogluturate is further increased by treatment of reaction products with acid.

Journal Article↗
PubMed1966

Microbial growth on C1 compounds. Incorporation of C1 units into allulose phosphate by extracts of Pseudomonas methanica.

1. Incubation of cell-free extracts of methane- or methanol-grown Pseudomonas methanica with [(14)C]formaldehyde and d-ribose 5-phosphate leads to incorporation of radioactivity into a non-volatile product, which has the chromatographic properties of a phosphorylated compound. 2. Treatment of this reaction product with a phosphatase, followed by chromatography, shows the presence of two compounds whose chromatographic properties are consistent with their being free sugars. 3. The minor component of the dephosphorylated products has been identified as fructose. The major component has been identified as allulose (psicose) on the basis of co-chromatography, co-crystallization of the derived phenylosazone and dinitrophenylosazone with authentic derivatives of allulose and behaviour towards oxidation with bromine water. 4. It is suggested that the bacterial extracts catalyse the condensation of a C(1) unit identical with, or derived from, formaldehyde with ribose 5-phosphate to give allulose 6-phosphate. 5. Testing of hexose phosphates and pentose phosphates as substrates has so far shown the reaction to be specific for ribose 5-phosphate. 6. The condensation reaction is not catalysed by extracts of methanol-grown Pseudomonas AM1. 7. A variant of the pentose phosphate cycle, involving this condensation reaction, is suggested as an explanation for the net synthesis of C(3) compounds from C(1) units by P. methanica.

Autoradiography↗