المؤلفون: Tilman Grune, Miriam Strosova, Jana Karlovska, Corinne M. Spickett, Lubica Horakova, Zuzana Orszagova

المصدر: General Physiology and Biophysics. 28:195-209

مصطلحات موضوعية: SERCA, Hypochlorous acid, Physiology, Biophysics, Calcium-Transporting ATPases, Antioxidants, Protein Carbonylation, chemistry.chemical_compound, Adenosine Triphosphate, medicine, Animals, Nucleotide, Chromans, Binding site, Muscle, Skeletal, chemistry.chemical_classification, Dose-Response Relationship, Drug, Endoplasmic reticulum, Skeletal muscle, General Medicine, Oxidants, Hypochlorous Acid, Calcium ATPase, Kinetics, Oxidative Stress, Sarcoplasmic Reticulum, medicine.anatomical_structure, chemistry, Biochemistry, Calcium, Rabbits, Trolox, Oxidation-Reduction

الوصف: Hypochlorous acid (HOCl) concentration-dependently decreased ATPase activity and SH groups of pure Ca-ATPase from sarcoplasmic reticulum (SERCA) of rabbit skeletal muscle with IC(50) of 150 micromol/l and 6.6 micromol/l, respectively. This indicates that SH groups were not critical for impairment of Ca-ATPase activity. Pure Ca-ATPase activity was analysed individually with respect to both substrates, Ca(2+) and ATP. Concerning dependence of ATPase activity on HOCl (150 micromol/l) as a function of free Ca(2+) and ATP, V(max) of both dependences decreased significantly, while the affinities to individual substrates were not influenced, with the exception of the regulatory binding site of ATP. On increasing HOCl concentration, fluorescence of fluorescein-5-isothiocyanate (FITC) decreased, indicating binding of HOCl to nucleotide binding site of SERCA. A new fragment appeared at 75 kDa after HOCl oxidation of SR, indicating fragmentation of SERCA. Fragmentation may be associated with protein carbonyl formation. The density of protein carbonyl bands at 75 and 110 kDa increased concentration- and time-dependently. Trolox (250 micromol/l) recovered the Ca-ATPase activity decrease induced by HOCl, probably by changing conformational properties of the Ca-ATPase protein. Trolox inhibited FITC binding to SERCA.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2e9a5305e44351d313bbd4a6b5aac23cTest
https://doi.org/10.4149/gpb_2009_02_195Test

المؤلفون: Tilman Grune, Anke Schwendel, Rolf Uhlig, Hermann-Georg Holzhütter, Werner Siems

المصدر: Scopus-Elsevier

مصطلحات موضوعية: Purine, Clinical Biochemistry, Biology, Models, Biological, Biochemistry, Mice, chemistry.chemical_compound, Allantoin, medicine, Animals, Computer Simulation, Nucleotide, Carbon Radioisotopes, Carcinoma, Ehrlich Tumor, Peritoneal Neoplasms, chemistry.chemical_classification, Mice, Inbred ICR, Catabolism, Cell Biology, General Medicine, medicine.anatomical_structure, Liver, chemistry, Purines, Hepatocyte, Uric acid, Female, Flux (metabolism), Nucleoside

الوصف: Mouse hepatocytes from healthy control mice and from Ehrlich ascites tumour-bearing mice were used for tracer-kinetic studies of purine catabolism of liver cells during different periods of tumour growth. The dynamics of the radioactive tracers were modelled mathematically by a system of differential equations. Computer simulations, i.e. direct fitting of numerical solutions of these equations to the observed time-courses of metabolites and specific radioactivites, enables one to estimate unknown kinetic parameters of a simplified model of pathways of hepatic purine catabolism in tumour-bearing mice. There occurred great differences of metabolic flux rates between control hepatocytes, hepatocytes of mice during the proliferating period of tumour growth (6th day after inoculation of the tumour) and hepatocytes of mice during the resting period of tumour growth (12th day after inoculation of the tumour). The final purine degradation of hepatocytes prepared during the proliferating period was lower in comparison with that of control hepatocytes, but it was markedly higher in hepatocytes prepared during the resting period of tumour growth. The changes in hepatocyte purine catabolism during the proliferating period of tumour growth argue for transitions which aim at the maintenance of high purine nucleotide levels in the liver itself rather than for an increased nucleoside and nucleobase supply for the tumour. This suggestion is in accordance with the increased ATP level of the liver during the proliferating phase of tumour growth. The drastic acceleration of the final steps of hepatic purine catabolism forming uric acid and allantoin during the resting period of tumour growth was predominantly due to increased flux rate from xanthosine and guanine in accordance with increased catabolism of monophosphorylated nucleotides.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::feeceb03a6687e4934668c099c384d08Test
https://doi.org/10.1002/cbf.290120102Test

المؤلفون: Tilman Grune, Werner Siems

المصدر: Europe PubMed Central

مصطلحات موضوعية: chemistry.chemical_classification, Purine, Base Composition, Chromatography, Erythrocytes, Molecular mass, General Chemistry, High-performance liquid chromatography, Nucleobase, Chromatographic separation, chemistry.chemical_compound, chemistry, Purines, Synovial Fluid, Animals, Humans, Nucleotide, Sample preparation, Quantitative analysis (chemistry), Digestive System, Chromatography, High Pressure Liquid

الوصف: An overview of high-performance liquid chromatographic separation techniques (reversed-phase and ion-pair reversed-phase) used in the analysis of purine ribonucleotides, ribonucleosides and nucleobases, including procedures for sample preparation, is given. Coverage of the separation techniques is extended to the measurement of specific radioactivities of these compounds in tracer kinetic experiments for metabolic flux rate analyses. This article is focused on the development and adaptation of reversed-phase separation techniques for nucleotides, nucleosides and bases that are used to examine a variety of biomedical problems. The investigation of purine nucleotide metabolic disorders or physiological transition in the pathomechanisms of different diseases and syndromes or in cell maturation processes, respectively, requires the application of chromatographic separation to a multitude of tissues and body fluids. These samples vary greatly in concentrations of purine compounds with low molecular mass, from ca. 5 m M to ca. 0.5 μ M . The advantages and disadvantages of different techniques are critically discussed.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::be3c48eeb9a2bf0077bc85161378a740Test
http://europepmc.org/abstract/med/8227254Test

المؤلفون: Tilman Grune, R.T. Toguzov, Pimenov Am, G. Gerber, Werner Siems, Yurii V. Tikhonov

المصدر: Europe PubMed Central

مصطلحات موضوعية: Erythrocytes, Ammonium phosphate, Buffers, High-performance liquid chromatography, chemistry.chemical_compound, Mice, Column chromatography, Potassium phosphate, Animals, Nucleotide, Purine metabolism, Carcinoma, Ehrlich Tumor, Chromatography, High Pressure Liquid, chemistry.chemical_classification, Mice, Inbred ICR, Chromatography, Muscles, General Chemistry, Ribonucleotides, Phosphate, chemistry, Liver, Purines, Female, Indicators and Reagents, Ribonucleosides, Quantitative analysis (chemistry)

الوصف: The pool of purine compounds was analysed in liver, skeletal muscle and blood of mice during the growth of Ehrlich ascites tumour cells. Three fast isocratic high-performance liquid chromatographic methods were used. (1) Determination of nucleotides by an isocratic ion-pair reversed-phase chromatography with a 10 mM ammonium phosphate buffer containing acetonitrile and tetrabutylammonium phosphate. (2) Separation of nucleosides and nucleobases in cell extracts by a reversed-phase system with methanol and 50 mM potassium phosphate buffer as eluent. (3) Nucleosides and nucleobases in body fluids were analysed by a reversed-phase system with 10 mM potassium phosphate containing methanol. These methods allow the rapid determination of purine compounds in small biological samples from various cell types and body fluids, with high accuracy and sensitivity. The pool of cellular nucleotides increased during the exponential phase of tumour growth. Adenosine accumulated significantly in all tissues in the stationary phase of tumour growth.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::51a5f86e51f96aa12a80553186c97c63Test
http://europepmc.org/abstract/med/2061396Test