Purification and properties of rat liver adenine phosphoribosyltransferase

Kenimer, James G.; Young, Leona G.; Groth, D.P.

doi:10.1016/0005-2744(75)90098-4

Cited by 20 publications

(10 citation statements)

References 26 publications

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“…However, under certain conditions (absence of glycerol and low levels of MgCl,), APRT was unstable and gel filtration with Sephadex resulted in a 70% loss of enzyme activity (data not shown). Similar results have been reported with the APRTs from Ehrlich ascites tumor cells, rat liver, Escherichia coli and human erythrocytes (Hod and Henderson 1966, Hochstadt-Ozer and Stadtman 1971, Thomas et al 1973, Kenimer et al 1975.…”

Section: 5supporting

confidence: 85%

Purification and characterization of adenine phosphoribosyltransferase from Arabidopsis thaliana

Lee

Moffatt

1993

Physiologia Plantarum

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Lee, D, and Moffatt, B. A. 1993. Purification and characterization of adenine pbosphoribosyltransferase from Arabidopsis ihaliana. -Physiol, Plant, 87: 483-492, Adenine phosphoribosyltransferase (APRT; EC 2.4.2,7) from Arabidopsis ihaliana was purified approximately 3800-foid. to apparent homogeneity. The purification procedure involved subjecting a leaf extract to heat denaturation, {NHjjiSOj precipitation, Sephadex G-2S salt separation, ultracentrifugation and liquid chromatography on Diethyiaminoethyl Sephacel, Phenyi Sepharose CL-4B, Blue Sepharose CL-6B and adenosine 5'-monophosphate-Agarose. The purified APRT was a homodimer of approximately 54 kDa and it had a specific activity of approximately 3(X) nmol (mg total protein) ' min '. Under standard assay conditions, the temperature optimum for APRT activity was 65°C and the pH optimum was temperature dependent. High enzyme activity was dependent upon the presence of divalent cations (Mn-' or Mg-*). In the presence of MnCI,, other divalent cations (Mg-*, Ca-*, Ba-*, Hg-* and Cd-*) inhibited the APRT reaction. Kinetic studies indicated that 5-phosphoribose-1-pyrophosphate (PRPP) caused substrate inhibition whereas adenine did not. The K^ for adenine was 4.5±1.5 (lA/, the K^ for PRPP was 0.29±0.06 mM and the K, for PRPP was L96±0.45 mM. Assays using radiolabelled eytokinins showed thai purified APRT can also catalyze the phosphoribosylation of isopentenyladenine and benzyladenine. The K^ for benzyladenine was approximately 0.73+0.06 mM.

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Section: 5supporting

confidence: 85%

Purification and characterization of adenine phosphoribosyltransferase from Arabidopsis thaliana

Lee

Moffatt

1993

Physiologia Plantarum

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“…In our case, the nature of the possible intermediate is difficult to assess, but Groth and Young (1971) have proposed the existence of an E-ribosyl-phosphate intermediate that has never been isolated, the problem remaining unsolved. The molecular weight, estimated at 42,000, is close to that described for the human erythrocyte enzyme (38,000; Holden et al, 19759, whereas the enzymes from rat liver (Kenimer et a]., 1975) and wheat germ (Chen et al, 1982) show smaller molecular weights: 22,000 and 23,000, respectively. Adenosine kinase activity in adrenal medulla was 90 mU/g fresh weight, clearly higher than values reported by Yamada et al (1980) or Phillips and Newsholme (1979) for rat brain, but lower than those found in vertebrate livers by Arch and Newsholme (1978).…”

Section: Discussionsupporting

confidence: 72%

“…APRT activity in adrenal medulla was found mainly in the cytosolic fraction, as occurs with the enzyme from a great variety of sources. As shown for the enzymes from rat liver (Kenimer et al, 1975) and human erythrocytes (Thomas et al, 1973), APRT from adrenal medulla exhibits initial burst synthesis of AMP, even at 0°C and 1 mM MgC1, and centrifuged at 100,000 g for 60 min to obtain the cytosolic extract (100,000 X g supernatant).…”

Section: Discussionmentioning

confidence: 99%

Purine Nucleotide Synthesis in Adrenal Chromaffin Cells

Rotllán

Miras-Portugal

1985

Journal of Neurochemistry

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The synthesis of purine nucleotides from the salvage precursors adenine and adenosine, and from the de novo precursors formate and glycine, was studied in isolated adrenal chromaffin cells. Both [8-14C]adenine and [8-14C]adenosine from extracellular medium are effectively incorporated into intracellular nucleotides. [14C]Formate and [U-14C]glycine are also incorporated, but de novo synthesis is clearly lower than synthesis from salvage precursors, although similar to de novo synthesis in liver. The enzymes responsible for adenine and adenosine salvage, adenine phosphoribosyltransferase and adenosine kinase, were purified about 1,500-fold. Both enzymes are mainly cytosolic and exhibit a similar molecular weight of around 42,000. The results suggest that chromaffin cells can replenish their intracellular nucleotides lost during the secretory event by an active synthesis from salvage and de novo precursors.

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“…Adenine incorporation into nucleotides in liver cells incubated with 200 ,uM adenine was taken as a measure of PPnificantly overall glucose oxidation by about 5 0 % . ribose-P availability in these cells because liver adenine The oxidative branch of the pentose phosphate pathway phosphoribosyltransferase (EC 2.4.2.7) has a high and the recycling of pentose phosphates were not sig-affinity for PP-ribose-P and for adenine (23,24), and nificantly changed in the presence of both hormones.…”

Section: Discussionmentioning

confidence: 98%

Purine synthesis de novo and its regulation in rat hepatocytes

Rosiers¹,

Lalanne²,

Willemot³

1980

Can. J. Biochem.

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Purine synthesis de novo and its regulation were studied in freshly isolated hepatocytes from fed adult male rats. The cells incorporated [14C]formate mainly into purine ribonucleotides. The immediate effect of increasing the concentration of inorganic phosphate in the incubation medium was an increase in 5-phosphoribosyl 1-pyrophosphate (PP-ribose-P) availability and a stimulation of purine synthesis de novo. However, prolonged incubation of cells in 25 mM phosphate resulted in a decreased PP-ribose-P availability and purine synthesis de novo. Methylene blue and phenazine methosulfate decreased PP-ribose-P availability and purine synthesis de novo although they stimulated considerably the pentose phosphate pathway. In contrast, epinephrine and glucagon increased significantly PP-ribose-P availability and purine synthesis de novo, but they did not change the activity of the pentose phosphate pathway. These results show a relationship between PP-ribose-P availability and purine synthesis de novo in rat hepatocytes. They emphasize the complexity of the regulation of PP-ribose-P availability.

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Purification and properties of rat liver adenine phosphoribosyltransferase

Cited by 20 publications

References 26 publications

Purification and characterization of adenine phosphoribosyltransferase from Arabidopsis thaliana

Purification and characterization of adenine phosphoribosyltransferase from Arabidopsis thaliana

Purine Nucleotide Synthesis in Adrenal Chromaffin Cells

Purine synthesis de novo and its regulation in rat hepatocytes

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