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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The energy metabolism of rat thymus cells has been investigated using preparations of isolated cells obtained by mechanical treatment of whole organs. The addition of glycolytic substrates such as glucose, pyruvate and lactate stimulates the endogenous respiration of these cells by 50%. On the other hand, succinate, glutamate and malate do not produce any effect. Oligomycin (10 mug/ml) inhibits both endogenous and glucose stimulated respiration by about 40%; 2, 4-DNP (50 muM) increases by 100% glucose induced respiration. The results obtained by using mitochondrial and glycolytic inhibitors as well as aminoxyacetic acid (AOA) and following pyridine nucleotides redox changes, support the idea that in thymus cells glucose is able to induce a great enhancement of O2 consumption both by raising the level of endogenous pyruvate and feeding the mitochondrial respiratory chain with cytosolic reducing equivalents, through an active malate-aspartate shuttle. Thymus cells exhibit a high Pasteur effect (74%). Both AOA and 2,4 DNP are able to stimulate aerobic lactate accumulation by 200% and 100% respectively, indicating that either the redox or phosphate potential do influence the rate of aerobic glycolysis in isolated thymus cells. Similar experiments are also reported on other cells with well known biochemical characteristics.
Mol Cell Biochem 1975 Jul 31
PMID:Energy metabolism of isolated rat thymus cells. 24 Oct 10

3-Aminopyridine adenine dinucleotide phosphate (AADP) was prepared from NADP and 3-amino-pyridine through the pig brain NADase-catalyzed pyridine base exchange reaction. The purified dinucleotide was chemically characterized and spectral properties of the compound were determined. The importance of the application of AADP in studies of NADP-requiring biochemical processes was indicated by the demonstration of AADP as an effective inhibitor of five NADP-requiring enzymes, by the demonstration of the fluorescence enhancement on the binding of AADP to yeast glucose-6-phosphate dehydrogenase when glucose-6-phosphate is present, and by the functioning of AADP as a fluorimetric substrate for snake venom nucleotide pyrophosphatase.
Mol Cell Biochem 1975 Aug 30
PMID:Studies of 3-aminopyridine adenine dinucleotide phosphate. 24 Oct 12

Cyanogen-induced phosphorylation of D-fructose at pH 8.8 led to the formation of a phosphorylated sugar identified as alpha-D-furcto-pyranose 2-phosphate on the basis of its chromatographic and electrophoretic properties, its lability to hydrolysis by alkaline phosphatase, the rate of its acid-catalysed hydrolysis, the results of periodate oxidation and optical rotatory measurements.
J Mol Evol 1975 Oct 03
PMID:Cyanogen induced phosphorylation of D-fructose. 24 63

1. Hypoxanthine--guanine phosphoribosyltransferase (HGPRT) activity was measured in erythrocyte haemolysates and quadriceps muscle extracts of normal and dystrophic 129 ReJ and C57 BL/6J mice with [8(-14)C]hypoxanthine as substrate and 5-phosphorylribose 1-pyrophosphate as a ribose 5-phosphate donor. [8(-14)C]Inosine monophosphate formed was separated by high-voltage electrophoresis and radioactivity was measured by liquid-scintillation counting. 2. In erythrocyte haemolysates, HGPRT activity was similar in normal and dystrophic C57 BL/6J mice but was significantly higher in dystrophic than in normal 129 ReJ mice. Elevated enzyme activity was observed only in mice that were clinically severely affected. 3. In muscle homogenates, HGPRT activity was significantly higher in dystrophic than in normal animals of both 129 ReJ and C57 BL/6J mice. Enzyme activity was not related to the severity of the disease. 4. It is suggested that changes in erythrocytes are secondary to the dystrophic process and that elevated HGPRT activity in skeletal muscle may be related to abnormal energy metabolism, possibly via the pentose monophosphate shunt.
Clin Sci Mol Med Suppl 1978 Dec
PMID:Hypoxanthine--guanine phosphoribosyltransferase activity in blood and skeletal muscles of normal and dystrophic mice. 28 49

Ribosomal proteins of the dimorphic fungus Mucor racemosus were isolated and characterized by 2-dimensional gel electrophoresis. Proteins from ribosomes of the yeast and mycelial phase were compared, and were found to be qualitatively indistinguishable. The only consistent difference in the patterns of proteins was in a protein of the 40S subunit, S-6. This protein was phosphorylated in yeast and hyphae forms, but not in asexual sporangiospores. Studies on protein S-6 showed that it contained 3 phosphate residues per molecule of protein when maximally phosphorylated. In this form 3 different tryptic peptides were shown to contain a single phosphoserine. The S-6 protein also existed in forms containing 1 or 2 phosphates per molecule, depending on growth conditions.
Mol Gen Genet 1979 Aug
PMID:Ribosomal proteins of the dimorphic fungus, Mucor racemosus. 29 24

Two types of reactivities of thiophosphates have been demonstrated: one being nucleophilic displacement by the P-S moiety of nucleoside phosphorothioates and the other, phosphorylation via P-S cleavage as the driving force. We have designed a system where both displacement on carbon and P-S cleavage are possible. Adenosine derivatives have been synthesized with 5'-deoxy-5'-chloro and 5'-O-tosyl substitutions as leaving groups utilizing the 3'-O-phosphorothioate as the biphilic center. The main products of cyclization were 5'-O-tosyl and 5'-chloroadenosine 2':3'-cyclic phosphate. Formation of 3':5'-S-phosphorothioate was slow even using an excellent leaving group. This is possibly due to hydrogen bonding between the 2'-OH and the neighboring P-O.--KOH hydrolysis of the cyclic phosphorothioate yielded 2'(3') phosphorothioates in a 1:1 ratio. The 2' and 3' isomers were separated and used to study the relative rates of cyclization. The cyclization via P-S cleavage of 2'(3')-O-phosphorothioates showed that the 2' isomer was more reactive. This is the first report of superior reactivity of the 3'-OH of a ribonucleoside.
J Mol Evol 1978 May 12
PMID:Mechanistic possibilities in prebiotic thiophosphate chemistry. 30 64

A previous paper (Mahler, M. 1978 J. Gen. Physiol. 71:559--580) describes the time-course of the suprabasal rate of oxygen consumption (delta QO2) in the sartorius muscle of R. pipiens after isometric tetani of 0.1--1.0 s at 20 degrees C. To test whether these were the responses to impulse changes in the rate of ATP hydrolysis, we compared the total suprabasal oxygen consumption during recovery (delta[O2]) with the amount of ATP hydrolyzed during a contraction, measured indirectly as the decrease in creatine phosphate (delta[CP]O). If suprabasal ATP hydrolysis during recovery is negligible in comparison with that during contraction, delta[CP]0/delta[O2] should approximate the P:O2 ratio for oxidative metabolism, which has an expected value of 6.1--6.5. We found: formula; see text. We conclude that in this muscle at 20 degrees C: (a) after a tetanus of 0.2--1.0 s, delta QO2(t) can be considered the response to an impulse increase in the rate of ATP hydrolysis; (b) the reversal during recovery of unidentified exothermic reactions occurring during the contraction (Woledge, R. C. 1971. Prog. Biophys. Mol. Biol. 22:39--74) can be coupled to an ATP hydrolysis that is at most a small fraction of delta[CP]0; (c) the pooled mean for delta[CP]0/delta[O2], 6.58 +/- 0.55, sets an experimental lower bound for the P:O2 ratio in vivo.
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PMID:The relationship between initial creatine phosphate breakdown and recovery oxygen consumption for a single isometric tetanus of the frog sartorius muscle at 20 degrees C. 31 12

The evidence that all energy transducing membranes can generate a proton electrochemical potential difference, delta micronH, across the membrane and that this potential can be used to transfer energy among energy transducing units and to generate ATP, has increased the interest for the view that delta micronH plays an obligatory role in energy transduction and ATP synthesis. In the present article we shall concentrate on two experimental questions related with the generation and role of delta micronH: (a) the charge/site ratio; (b) the relation between the proton electrochemical potential on one side and the cation electrochemical potential, the phosphate potential and the redox potential on the other. We shall then discuss the view that energy transduction corresponds to a molecular energy machine rather than to a fuel cell.
Mol Cell Biochem 1977 Sep 09
PMID:The generation of the proton electrochemical potential and its role in energy transduction. 33 72

We have studied the biosynthesis of T4 induced tRNA's upon infection of E. coli BE cells in low phosphate (l.p.) medium (10(-4) M PO---4). Under out experimental conditions the onset of phage DNA synthesis occurs about 15 min after infection, while the first intracellular phage appears one hour later. Amounts of newly synthesized DNA and phage burst size are equivalent to the values obtained in standard (M9) medium (10(-1) M PO---4). We present evidence that the synthesis of mature tRNA's and of at least one dimeric precursor drastically declines 20 min after infection. In addition we show that T4 induced tRNA molecules are stable and that the triphosphate nucleoside precursor pool does not change significantly during infection. Therefore we conclude that T4 induce tRNA molecules behave similarly to other early gene products.
Mol Gen Genet 1977 Sep 21
PMID:Regulation of the intracellular concentration of T4 induced tRNA. 33 17

A mutation pgi1 in the yeast Saccharomyces cerevisiae conferring deficiency of the glycolytic enzyme glucose 6-phosphate isomerase is characterised genetically. The mutation segregates 2+:2- in tetrads from diploids heterozygous for the mutant phenotype. The mutation is semi-dominant and is located on the right arm of chromosome II in the order: tsm134--lys2--pgi1--tyr1 approximately 15 map units from tyr1. The mutation pgi1 defines the structural gene of glucose 6-phosphate isomerase and can be suqpressed intragenically giving revertants that have an unstable enzyme. In one temperature-sensitive revertant no enzyme activity in excess of the mutant level could be detected although fructose 6-phosphate was converted to glucose 6-phosphate in vivo. The suppressor locus in this revertant is dominant and is unlinked to the pgi1 locus.
Mol Gen Genet 1977 Nov 04
PMID:Genetic studies with a phosphoglucose isomerase mutant of Saccharomyces cerevisiae. 34 Aug 92


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