The rabbit reticulocyte is capable of utilizing purines and their ribosyl derivatives for nucleoside triphosphate formation. Adenine, adenosine, hypoxanthine, and inosine are used extensively for the synthesis of adenosine triphosphate. Xanthine, guanine, and guanosine are utilized primarily for the synthesis of guanosine triphosphate. The inhibitor 6-diazo-S-oxo-L-norleucine inhibits the utili...

These studies examined the effect of dicumarol on xanthine dehydrogenase (XDH), an enzyme recently shown to bioreduce mitomycin C. Dicumarol, which has previously been shown to inhibit xanthine oxidase (XO), inhibited both XDH and XO mediated conversion of xanthine to uric acid but potentiated the metabolism of mitomycin C by XDH and XO. Formation of 2,7-diaminomitosene following mitomycin C bi...

The enzyme, xanthine oxidase, has been implicated as a major source of destructive free radicals in ischemia-reperfusion injury associated with a range of pathological states [l]. Enzymic activity has been detected in many mammalian tissues [4] by using, variously, spectrophotometric [51, radiometric[6] and fluorimetric [71 assays. Apart from bovine milk fat globule membrane, which has long pro...

Oxidative stress plays an important role in the progression of vascular endothelial dysfunction. The two major systems generating vascular oxidative stress are the NADPH oxidase and the xanthine oxidase pathways. Allopurinol, a xanthine oxidase inhibitor, has been in clinical use for over 40 years in the treatment of chronic gout. Allopurinol has also been shown to improve endothelial dysfuncti...

A B S T R A C T A case of xanthinuria is briefly described, and the results of in vivo studies with 4C-labeled oxypurines are discussed. The data demonstrate that the rate of the turnover of uric acid is normal, despite an extremely small uric acid pool. Xanthine and hypoxanthine pools were measured and their metabolism evaluated. The bulk of the daily pool of 276 mg of xanthine, but only 6% of...

HE conversion of 2-amino-4-hydroxypteridine into isoxanthopterin in wildtype Drosophila melanogaster has been demonstrated and investigated by several groups (FORREST, GLASSMAN and MITCHELL 1956; HADORN and SCHWINCK 1956; NAWA, TAIRA and SAKAGUCHI 1958). This reaction is catalyzed by an enzyme which will also catalyze the oxidation of hypoxanthine through xanthine into uric acid, xanthopterin i...

Introduction It is now appropriate to discuss fine details of the mechanism of action of xanthine oxidase because of the extensive spectroscopic and kinetic evidence available; this is especially so since this has recently been supplemented by X-raycrystallographic data. Much of the information has been reviewed comprehensively [1,2] and is also discussed in this volume [3,4]. In this article w...

We present resonant two-photon ionization (R2PI), UV-UV, and IR-UV double resonance spectra of xanthine seeded in a supersonic jet by laser desorption. We show that there is only one tautomer of xanthine which absorbs in the wavelength range of 36 700 to 37 700 cm(-1). The IR-UV double resonance spectrum shows three strong bands at 3444, 3485, and 3501 cm(-1), all of which we assign as N-H stre...

Fennel, Foeniculum vulgare Mill. (Apiaceae) is an aromatic plant, with medicinal and culinary applications, widely naturalized worldwide, especially near the see coasts and riversides. Fennel has long been used in Iran as a traditional remedy against gout. The objective of our study was to uncover the scientific basis of this traditional gout therapy. Different plant parts were extracted by met...