المؤلفون: John Mowbray, Philip Freeman, Brinda Patel

المصدر: Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1457:273-277

مصطلحات موضوعية: Mitochondrial intermembrane space, Biophysics, Brain purinogen, Liver purinogen, Biology, Kidney, Biochemistry, Rats, Sprague-Dawley, chemistry.chemical_compound, Adenosine Triphosphate, Adenine nucleotide, Heart purinogen, medicine, Animals, Muscle purinogen, Muscle, Skeletal, Chromatography, High Pressure Liquid, Phosphoglycerate kinase, Adenine Nucleotides, Myocardium, Brain, Skeletal muscle, Cell Biology, Phosphate, Molecular biology, Mitochondria, Rats, medicine.anatomical_structure, Liver, chemistry, Kidney purinogen, Glycerophosphates, ATP polymer, Phosphorylation, Intracellular

الوصف: Here, we describe an assay for the tissue content of purinogen, a highly phosphorylated labile polymer containing ATP and phosphoglycerate found in the mitochondrial intermembrane space. We report the purinogen content (as adenine nucleotide equivalents) of rat heart and, for the first time, of rat liver, kidney, brain and mixed skeletal muscle. The findings show that purinogen contains very significant proportions of cell adenine nucleotides ranging from 25% of the free pool in brain and skeletal muscle to 135% of it in kidney. The evidence that purinogen may form a controlled intracellular reservoir of inorganic phosphate is briefly discussed.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::94d475ed4a525b1f2ec0a2886cbbaf05Test
https://doi.org/10.1016/s0005-2728Test(00)00109-2

المؤلفون: Brinda Patel, John Mowbray

المصدر: Biochemistry and cell biology = Biochimie et biologie cellulaire. 69(9)

مصطلحات موضوعية: Purine, Cell, Mitochondria, Liver, Mitochondrion, Creatine, Kidney, Biochemistry, Mitochondria, Heart, chemistry.chemical_compound, Adenosine Triphosphate, medicine, Animals, Nucleotide, Molecular Biology, chemistry.chemical_classification, Chemistry, Phosphoric Diester Hydrolases, Myocardium, Substrate (chemistry), Cell Biology, Nuclear magnetic resonance spectroscopy, Phosphate, Rats, medicine.anatomical_structure, Liver, Glycerophosphates, Biophysics

الوصف: Introduction Although in recent times the application of nmr spectroscopy to living tissues has tended to confirm the role of free ADP in regulating oxidative metabolism (Chance et al., Proc. Natl. Acad. Sci. U.S.A., 83, 9458-9462, 1986), this is only so provided the ADP concentration is below a relatively low threshold value ( 50 pM). What is not clear are the mechanisms that restrain the ADP at this threshold, and nmr studies of the perfused rat heart (From et al., FEBS Lett., 206, 257-261, 1986) and intact dogs (Balaban et al., Science, 232, 1 121-1 123, 1986) have emphasized that respiratory control of heart mitochondria is not a function of free ADP concentration when this threshold is reached. Even more striking and difficult to explain is what limits the fall of ATP concentrations for up to tens of minutes when energy production is severely limited in hearts by ischaemia, while a "buffer" substrate like creatine phosphate disappears in tens of seconds; or again how the ATP pool is apparently replenished periodically during long-term ischaemia as nmr studies of frog muscle seem to show (Keidel et al., Res. Exp. Med., 84, 73-84, 1984). Similar experiments with perfused rat livers found nmr resonances for ATP declining faster than extracted ATP (Murphy et al., Biochemistry, 27, 526-528, 1988). The proposal that this missing nucleotide represented an nmr -invisible pool confined to the mitochondria1 matrix is challenged by the findings that all the ATP is nmr visible in isolated mitochondria (Hutson et al., Biochemistry, 28,4325-4332, 1989) and in the perfused heart (Humphrey and Garlick, Circulation, 80, 498, 1989). By contrast, on the related problem of cell inorganic phosphate concentrations, there is agreement that somewhat less than 50% of the extractable pool is ever nmr visible (see Humphrey et al., Eur. J. Biochem., 191, 755-759, 1990). The inference is that additional new information is required.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2c2800b81eee5bddbddc1999e6193c5eTest
https://pubmed.ncbi.nlm.nih.gov/1665334Test

المؤلفون: M. Holness, John Mowbray, A. Crespo-Armas

المصدر: FEBS Letters. 177:231-235

مصطلحات موضوعية: Male, medicine.medical_specialty, Biophysics, Mitochondria, Liver, Oxidative phosphorylation, Atractyloside, Mitochondrion, Biochemistry, Oxidative Phosphorylation, Hypothyroidism, Structural Biology, Internal medicine, Genetics, medicine, Animals, Molecular Biology, Triiodothyronine, biology, Adenine nucleotide translocator, Thyroid, Cell Biology, Nucleotidyltransferases, Rats, Kinetics, medicine.anatomical_structure, Endocrinology, Adenine nucleotide transport, Thyroidectomy, biology.protein, Phosphorylation, Mitochondrial ADP, ATP Translocases, Hormone

الوصف: Impaired phosphorylation efficiency in liver mitochondria from hypothyroid rats is paralleled by a defect in adenine nucleotide transport. Both of these lesions can be corrected within 15 min by a near-physiological dose of triiodo-L-thyronine. Measurement of the control strength of the translocator shows, however, that this step has a smaller share of the control for oxidative phosphorylation after thyroidectomy and that this is unaltered after 15 min by replacement therapy. Rapid control by triiodothyronine is thus exerted elsewhere than at this transfer and the effects of hormone on the translocator are likely to be indirect. Adenine nucleotide translocator Control strength Liver mitochondria Oxidative phosphorylation Triiodothyronine

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ce7b62353f35f40a07983bb000431e18Test
https://doi.org/10.1016/0014-5793Test(84)81289-2

المؤلفون: John Mowbray

مصطلحات موضوعية: Male, Cell, Malates, Palmitates, Biological Transport, Active, Hydroxybutyrates, Mitochondria, Liver, In Vitro Techniques, Biochemistry, chemistry.chemical_compound, Carnitine, medicine, Animals, Carbon Radioisotopes, Inner mitochondrial membrane, Pyruvates, Molecular Biology, Palmitoylcarnitine, Monocarboxylate transporter, biology, Myocardium, Transporter, Cell Biology, Pyruvate dehydrogenase complex, Mitochondria, Muscle, Rats, Kinetics, Membrane, medicine.anatomical_structure, chemistry, biology.protein, Lactates, medicine.drug, Research Article

الوصف: Several hydroxy- and keto-substituted monocarboxylates were found to undergo co- as well as counter-exchange across the mitochondrial membrane. The results argue against a simple Donnan system and may be explained by the existence of a transporter for monocarboxylates. In support of this explanation it was apparently possible to ‘pump’ pyruvate to the sucrose-inaccessible space by using the dicarboxylate transporter. Further, several aromatic and aliphatic analogues of pyruvate, but not of di- or tri-carboxylate transport inhibitors, have been shown to prevent pyruvate-exchange reactions. Palmitoylcarnitine was found to have a much stronger affinity for the carrier than either carnitine or pyruvate and the possible consequences of this for carnitine-palmitoylcarnitine exchange and on the control of the pyruvate dehydrogenase complex are explored. In view of the range of transport inhibitors and substrates it is suggested that the carrier has a fairly broad specificity. ‘Inhibitor-stop’ kinetic studies show that the speed of translocation of pyruvate at 1 degrees C is of the same order as malate. The possible correlation between the role of a hydroxy-keto acid transporter in substrate exchange and some whole animal experiments is briefly discussed. It is proposed that for reasons of control the cell will require membrane monocarboxylate transporters no less than di- or tri-carboxylate carriers.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::98395d6883c1ec7ca662cadd1768ba44Test
https://europepmc.org/articles/PMC1165504Test/