Pyrimidine Metabolism in Man. I. The Biosynthesis of Orotic Acid*†

Smith, Lloyd H.; Baker, Faith A.

doi:10.1172/jci103862

Cited by 86 publications

(40 citation statements)

References 25 publications

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“…Five sequential enzymes involved in the synthesis of UMP from carbamxl phosphate and aspartic acid have been assayed in human leukocytes and erythrocytes (5,39). None of these methods allows a quantitative approach to the biosynthesis of pyrimidine nucleotides in the intact organism.…”

Section: Discussionmentioning

confidence: 99%

“…Acidification of aliquots of this solution allowed trapping of the carbon dioxide in Hyamine base and counting in a Packard Tri-Carb liquid scintillation spectrometer at an efficiency of approximately 45 40 per cent. Orotic acid in the urine was identified by ascending paper chromatography in a propanol: HO: formic acid system (7: 2:1) through comparison with known standard (Rf approximately 0.40) and also from ultraviolet spectrophotometry of acid solutions of the eluted spots (5).…”

Section: Methodsmentioning

confidence: 99%

“…D,L-Carbamylaspartic acid-C1 (CAA-C"4), labeled in the ureide position, was synthesized as previously described (5). D,L-CAA-C14, labeled in the C-1 position (corresponding to the carboxyl carbon of orotic acid), was synthesized by alkaline hydrolysis of carboxyl-labeled dihydroorotic acid-C1' (5). Specific activity as utilized was approximately 0.2 /Ac per jsmole.…”

Section: Methodsmentioning

confidence: 99%

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Pyrimidine Metabolism in Man. V. The Measurement in Vivo of the Biochemical Effect of Antineoplastic Agents in Animal and Human Subjects*

Rabkin¹,

Frederick²,

Lotz³

et al. 1962

J. Clin. Invest.

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Many in v'ivo studies have been carried out on purine metabolism in man because of the presence of a readily available end product, uric acid. In the absence of a comparable unique end product, no previous over-all measurements of pyrimidine metabolism in the intact organism have been reported. Studies have been limited to the excretion of /8-aminoisobutyric acid, as a metabolite of thymine (1), the incorporation of pyrimidine precursors into circulating leukocytes (2), the induced urinary excretion of orotic acid and orotidine (3), and the spontaneous urinary excretion of certain trace pyrimidines (4). In this report a method is described for evaluating pyrimidine nucleotide synthesis in the intact organism, based on the release of carbon dioxide-C14 from carboxyl-labeled pyrimidine precursors. The usefulness of this procedure in defining the onset, degree, and duration of action of certain antimetabolites is illustrated by studies in rats, and in patients with leukemia. MATERIALS AND METHODSIntravenous injections of labeled compounds were given through indwelling jugular vein catheters to male albino rats, weighing 125 to 150 g. For collection of expired C1402, air was flushed through a closed metabolic chamber and the carbon dioxide trapped in 3 N NaOH. Acidification of aliquots of this solution allowed trapping of the carbon dioxide in Hyamine base and counting in a Packard Tri-Carb liquid scintillation spectrometer at an efficiency of approximately 45 per cent. Indwelling cystostomy catheters were operatively placed in rats for urinary studies. Sedation with perphenazine (Trilafon, Schering), and hydration with normal or hypotonic saline *

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Pyrimidine Metabolism in Man. V. The Measurement in Vivo of the Biochemical Effect of Antineoplastic Agents in Animal and Human Subjects*

Rabkin¹,

Frederick²,

Lotz³

et al. 1962

J. Clin. Invest.

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“…We also showed that C underwent DHOase-catalyzed metabolism in a myocyte suspension . DHOase is present in a variety of tissues including the heart, liver, and kidney (Kennedy, 1974) and in erythrocytes and leukocytes (Smith and Baker, 1959). However, although DHPase is present in the liver and the kidney, it is not present in the heart (Dudley et al, 1974;Hasinoff et al, 1991;Hamajima et al, 1996).…”

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confidence: 99%

The Dihydroorotase Inhibitor 5-Aminoorotic Acid Inhibits the Metabolism in the Rat of the Cardioprotective Drug Dexrazoxane and Its One-Ring Open Metabolites

Schroeder¹,

Patel²,

Hasinoff³

2008

Drug Metab Dispos

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Dexrazoxane [ICRF-187, Zinecard (Pfizer, New York, NY), Totect and Savene (TopoTarget, Copenhagen, Denmark)] (Fig. 1) is clinically used to reduce doxorubicin-induced cardiotoxicity (Hasinoff, 1998;Hasinoff et al., 1998;Cvetković and Scott, 2005;Hasinoff and Herman, 2007) and has just been approved in the United States for the prevention of anthracycline-induced extravasation injury (Hasinoff, 2008). There is now considerable evidence to indicate that the cardiotoxicity of doxorubicin may be because of iron-dependent oxygen free radical formation (Malisza and Hasinoff, 1995;Meyers, 1998;Hasinoff and Herman, 2007) on the relatively unprotected cardiac muscle. Dexrazoxane may act through its metal-chelating ringsopened hydrolysis product ADR-925 (Fig. 1), which can either remove iron from the iron-doxorubicin complex (Buss and Hasinoff, 1993) or bind free iron (Diop et al., 2000), thus preventing iron-based oxygen radical formation. Thus, dexrazoxane can be considered a prodrug analog of EDTA that is activated on hydrolysis to its one-ring open intermediates B and C, and then to its fully rings-opened form ADR-925 according to the scheme in Fig. 1 (Hasinoff, 1990(Hasinoff, , 1994a(Hasinoff, ,b, 1998Hasinoff and Herman, 2007).We previously showed that dexrazoxane is quickly metabolized to B and C, and then to ADR-925 in humans (Schroeder et al., 2003) and in rats . The rapid rate of hydrolysis of dexrazoxane and the rapid appearance of ADR-925 in plasma in vivo suggest that dexrazoxane first and then B and C are all enzymatically metabolized. We also showed that rats rapidly metabolized a mixture of B and C to ADR-925, which suggested that these metabolites were themselves enzymatically metabolized . We have shown that pure dihydropyrimidinase (DHPase) (EC 3.5.2.2) enzymatically hydrolyzes dexrazoxane to B and C but cannot enzymatically hydrolyze B and C to ADR-925 (Hasinoff et al., 1991;Hasinoff, 1993). We have also shown that another zinc hydrolase, dihydroorotase (DHOase) (EC 3.5.2.3), is able to enzymatically hydrolyze B and C to ADR-925 but does not act on dexrazoxane . Thus, it is hypothesized that DHPase and DHOase act sequentially and in concert to effect the full metabolism of dexrazoxane to its active metal ion-chelating form ADR-925. We also previously showed that B and C are rapidly formed from ABBREVIATIONS: ADR-925, N,NЈ-[(1S)-1-methyl-1,2-ethanediyl]bis[(N-(2-amino-2-oxoethyl)]glycine; B, N-(2-amino-2-oxoethyl)-N-[(1S)-2-(3,5-dioxo-1-piperazinyl)-1-methylethyl]glycine; C, N-(2-amino-2-oxoethyl)-N-[(2S)-2-(3,5-dioxo-1-piperazinyl)propyl]glycine; DHPase, dihydropyrimidine amidohydrolase or dihydropyrimidinase; DHOase, dihydroorotase; HPLC, high-pressure liquid chromatography; LDH, lactate dehydrogenase; AUC 5-120 , area-under-the-curve of concentration-time data for dexrazoxane or ADR-925 from 5 to 120 min.

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“…Assays were carried out on aspartate carbamyltransferase, dihydroorotase and dihydroorotic dehydrogenase ( Figure 1). The methods employed in separation of cells, sonication of leukocytes, hemolysis of erythrocytes and assay of the enzymes have been described in detail previously (7). In brief, each assay depended on the incorporation of a C14 precursor of high specific activity into a product which was then isolated …”

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Pyrimidine Metabolism in Man. Iii. Studies on Leukocytes and Erythrocytes in Pernicious Anemia*†

Smith¹,

Baker²

1960

J. Clin. Invest.

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Pyrimidine Metabolism in Man. I. The Biosynthesis of Orotic Acid*†

Cited by 86 publications

References 25 publications

Pyrimidine Metabolism in Man. V. The Measurement in Vivo of the Biochemical Effect of Antineoplastic Agents in Animal and Human Subjects*

Pyrimidine Metabolism in Man. V. The Measurement in Vivo of the Biochemical Effect of Antineoplastic Agents in Animal and Human Subjects*

The Dihydroorotase Inhibitor 5-Aminoorotic Acid Inhibits the Metabolism in the Rat of the Cardioprotective Drug Dexrazoxane and Its One-Ring Open Metabolites

Pyrimidine Metabolism in Man. Iii. Studies on Leukocytes and Erythrocytes in Pernicious Anemia*†

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