Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of replacement of extracellular Na+ by Li+, choline K+ or sucrose on cyclic AMP formation in pigeon erythrocytes has been investigated. Replacement of extracellular Na+ by Li+, choline or sucrose but not by K+ inhibited the stimulation by adrenalin of cyclic AMP formation, but had no detectable effect on cyclic AMP content in the absence of adrenalin. This inhibition was observed in the presence or absence of extracellular Ca2+. The relative inhibition caused by Na+ removal decreased with increasing adrenalin concentration. It was concluded that extracellular Na+ or K+ ions were required for maximal activation of adenylate cyclase by low concentrations of adrenalin, and that this effect of monovalent cations may have been due to an effect on the affinity of the receptor for adrenalin. The verapamil derivative D-600 also inhibited the stimulation by adrenalin of cyclic AMP formation. This effect occurred in the absence of extracellular Ca2+ and hence seemed to be unrelated to the inhibition by C-600 of the slow Ca2+ channel in electrically excitable tissues.
Mol Cell Endocrinol 1978 Jun
PMID:Effect of replacement of extracellular sodium ions and of D-600 on the activation by adrenalin of adenylate cyclase in intact pigeon erythrocytes. 68 Mar 36

Gluconeogenesis by isolated hepatocytes resulted in glucose release but insignificant rates of glycogen synthesis. The effectiveness of precursors was similar for hepatocytes from fed and starved chickens except for impaired gluconeogenesis from pyruvate when compared to lactate in lactate starved chicken hepatocytes. The impairment was caused by limitations in cytosolic NADH production as a result of the mitochondrial location of phosphoenolpyruvate carboxykinase in chicken liver. The order of effectiveness of precursors on hepatic gluconeogenesis was generally similar to the effects of precursors on increasing the plasma glucose concentration in vivo. The exceptions were caused by interactions with other precursors in vivo. The alteration of the NADH/NAD+ ratio by ethanol and ATP/ADP ratio by adenosine could play significant roles in the control of precursor conversion to glucose. Physiological glucagon concentrations stimulated gluconeogenesis from precursors entering the pathway both above and below the level of triose phosphates, and its effect were mimicked by dibutyryl cyclic AMP. Previous results on the effects of precursor and glucagon injection on the plasma glucose concentration of chickens in vivo can largely be explained by effects at the hepatic level. Isolated chicken and rat hepatocytes share many common features. Qualitatively the ordering of gluconeogenic effectiveness was similar but quantitive differences existed as a result of differing activities and cellular locations of enzymes. Neither preparation readily synthesised glycogen and the sensitivity to glucagon was similar.
Mol Cell Biochem 1978 Dec 22
PMID:Hepatic gluconeogenesis in chickens. 74 98

This article attempts to trace, from a personal point of view, the history of discoveries of allosteric phenomena in phosphorylase b and the later development of systematic attempts to fit the data into comprehensive theoretical models. Work from our own laboratory is emphasized, but we try to integrate this into the results from other investigators and show their contributions to our ideas and experiments. Finally, some recent unpublished data is presented together with some conclusions and predictions from a new hypothesis. The discoveries by Carl and Gerty Cori of the activation of phosphorylase by AMP, the inhibition of glucose and the enzymatic interconversion of two forms fo the enzyme with different control properties helped lay the foundations of our present understanding of allosteric mechanisms. The later discovery of the oligomeric nature of phosphorylase and its relationship to AMP binding served as a basis for many years of research into the structure-function relationships of phosphorylase and other enzymes. Data showing that AMP lowers the entropy of activation is discussed with respect to the role of the nucleotide and its binding close to the active site. The discovery of the control of phosphorylase b by common metabolites and the impetus this gave to the intensive kinetic studies of the last ten years, wherein fitting to theoretical models has been a common feature, is reviewed.
Mol Cell Biochem 1976 Mar 26
PMID:Studies on allosteric phenomena in glycogen phosphorylase b. 77 16

The reversible reaction catalyzed by ATP phosphoribosyltransferase favors the pyrophosphorolysis of phosphoribosyl-ATP (PR-ATP). The enzyme is inhibited by PR-ATP. To avoid this problem and measure with confidence initial rates of the transferase, we have purified more than one hundred fold the enzyme PR-ATP pyrophosphohydrolase, which irreversibly converts PR-ATP to PR-AMP. Using this coupled assay, we report on substrate kinetics and histidine inhibition studies of ATP phosphoribosyltransferase of Escherichia coli. 1. In the absence of histidine the variation of initial velocity as a function of ATP or phosphoribosyl pyrophosphate (PRPP) concentration, follows Michaelis-Menten kinetics, with ATP inhibiting at high concentrations. In the presence of histidine a change from hyperbolic to sigmoidal kinetics is observed. 2. Apparently AMP acts as a competitive inhibitor of ATP. 3. The bisubstrate kinetics gives a pattern of parallel lines, suggesting a double displacement mechanism. 4. The inhibition by histidine appears not to be cooperative or perhaps slightly negatively cooperative.
Mol Cell Biochem 1976 Jun 15
PMID:Kinetic properties of ATP phosphoribosyltransferase of Escherichia coli. 78 21

The mechanism of 5'-cytidilic acid stimulation of the reaction between 2'(3')-O-formylmethionine ester of 5'-adenylic acid and phenylalanyl-tRNA catalyzed by E. coli ribosomes has been studied. It has been shown that cytidilic acid binds to the donor site of the peptidyltransferase in the area which is usually occupied by the second nucleotide residue of the peptidyl-tRNA 3'-end. After the binding cytidilic acid stimulates effectively the donor activity of formylmethionine ester of adenylic acid. A number of compounds have been tested as possible stimulants. Both the chemical nature of stimulant and its conformation are important for the stimulating action. A hypothetic scheme is suggested explaining possible causative factors of peptidyl-tRNA translocation from the acceptor site to the donor site after peptide bond formation.
Mol Biol (Mosk)
PMID:[Donor site of E. coli ribosomal peptidyltransferase]. 80 87

The four enzymes deoxyriboaldolase, thymidine phosporylase, deoxyribomutase, and purine nucleoside phosphorylase have been synthesized in substantial amounts in a DNA-dependent in vitro system programmed with DNA containing the deo operon. The synthesis is greatly stimulated by deoxyribose-5-phosphate and cyclic AMP indicating that the deoR repressor and the catabolite activating protein (CAP) are highly active under our cell-free conditions. In contrast it has not yet been possible to observe a reproducible effect of the cytR repressor in vitro. The sequential appearance of active enzymes has confirmed the direction of transcription as being dra-tpp-drm-pup and has indicated that the four genes are transcribed into a single tetracistronic message.
Mol Gen Genet 1975
PMID:Regulated in vitro synthesis of the enzymes of the deo operon of Escerichia coli. properties of the DNA directed system. 81 Jun 59

1. The hepatic concentration of several nucleotides and metabolites was measured during the first few minutes after an intravenous load of fructose to mice. The first changes, observed at 30s, were a decrease in the concentration of Pi and a simultaneous accumulation of fructose 1-phosphate. The decrease in the concentrations of ATP and GTP proceeded more slowly. An increase in the concentration of IMP was detected only after 1 min and could therefore not be considered to be the cause of the accumulation of fructose 1-phosphate. 2. To explain the temporary burst of adenine nucleotide breakdown that occurs after a load of fructose, the kinetics of AMP deaminase (EC 3.5.4.6) from rat liver were reinvestigated at physiological (0.2 mM) concentration of substrate. For this purpose, a new radiochemical-assay procedure was developed. At 0.2mM-AMP a low activity could be measured, which was more than 90% inhibited by 5mM-Pi. ATP (3MM) increased the enzyme activity over 200-fold. Pi alone did not influence the ATP-activated enzyme, but 0.5mM-GTP caused a 60% inhibition. The combined effect of both inhibitors at their physiological concentrations reached 95%. 3. It is proposed that the rapid degradation of adenine nucleotides that occurs after a load of fructose is caused by a decrease in the concentration of both inhibitors, Pi and GTP, soon counteracted by the decrease in the concentration of ATP. 4. Some of the kinetic parameters of liver AMP deaminase were computed in terms of the concerted transition theory of Monod, Wyman & Changeux (1965) (J. Mol. Biol. 12, 88-118).
 ...
PMID:The mechanism of adenosine triphosphate depletion in the liver after a load of fructose. A kinetic study of liver adenylate deaminase. 86 6

Adenylyl-(5'leads to N)-amino acids containing as amino components, methyl esters of D-, L- and DL-phenylalanine, D-, L- and DL-tyrosine, and D-, L- and DL-tryptophan have been investigated by proton magnetic resonance (PMR) spectroscopy and circular dichroism (CD). The temperature and pD dependences of proton chemical shifts of these compounds have been studied. These data, together with the magnitudes of the upfield chemical shifts of the PMR signals of adenine and aromatic amino acids residues in adenylyl-(5'leads to N)-amino acids, have enabled us to construct conformational models of these compounds. The proposed conformation has been substantiated by the CD results. It is shown that in adenylyl-(5'leads to N)-amino acids the planes of adenine and amino acid aromatic moieties are roughly parallel. The aromatic rings of phenylalanine and tyrosine are localized approximately above the centre of adenine. In adenylyl-(5'leads to N)-D, -(L)-tryptophan, the six-membered rings of the indole overlaps the five-membraned ring of adenine indole partially overlaps the six-membered ring of adenine. A difference in the non-covalent interactions of D- and L-amino acids with nucleotides has been revealed. The mutual localization of the aromatic systems of AMP and the amino acids and also the positions of -OCH3 group with respect to the centre of the amino acid aromatic moiety differs in the series of the studied nucleotide derivatives of D- and L-amino acids.
Mol Biol (Mosk)
PMID:[The secondary structure of amides of adenylic acid containing D- and L-aromatic amino acids]. 94 May 56

Plasma membranes were isolated from thyroid cells obtained by trypsinization of porcine glands and maintained in culture conditions in the presence or absence of thyrotropin or dibutyryl cyclic AMP. The protein, phospholipid, cholesterol and sialic acid content of the 3 types of cell plasma membranes were very similar. High cholesterol and sialic acid content characterized these membranes. The amino acid and carbohydrate composition was similar to that shown for other eukaryotic plasma membranes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis disclosed the presence of more than 20 protein bands, of which six corresponded to glycoproteins.
Mol Cell Endocrinol
PMID:Chemical composition of porcine thyroid cell plasma membranes. 95 52

Collagen mRNA has already been purified and characterized by us. Its purity has now been enhanced by two different methods. Gel electrophoresis shows in either method, a single peak with the same mobility already reported: 1.05 X 10(6) daltons. Base composition analyses of collagen mRNA purified by either method were almost identical. Chemical analyses of the isolated polyadenylic acid stretch show that it is, 0.48 X 10(5) daltons-long, (about 140 nucleotides-long), contains 75% AMP, and is located at the 3' end of the polymer.
Mol Biol Rep 1976 Jul
PMID:Further studies on collagen mRNA: partial chemical characterization and polyadenylic acid sequence. 95 18


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>