Topic
Xanthine
About: Xanthine is a research topic. Over the lifetime, 4046 publications have been published within this topic receiving 129820 citations. The topic is also known as: Xanthine.
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TL;DR: In this paper, the assignment of N-H signals in the xanthine and thioxanthine series, as well as the effects of moisture, concentration and temperature on the n-H and C-H nmr spectral characteristics are discussed.
43 citations
TL;DR: The desulfo form of milk xanthine oxidase was reactivated by incubation with rhodanese with 50% of full activity recovered and native enzyme in the sulfo form with full activity was inactivated, indicating that the sulfur atom was exchanged during the incubation.
Abstract: The desulfo form of milk xanthine oxidase (xanthine: oxygen oxidoreductase, EC 1.2.3.2) was reactivated by incubation with rhodanese (thiosulfate: cyanide sulfurtransferase, EC 2.8.1.1), thiosulfate, and sulfhydryl reagent; 50% of full activity was recovered. No further reactivation occurred with additional incubation. It was also found that native enzyme in the sulfo form with full activity was inactivated by incubation with the same system, down to half of full activity and no further inactivation occurred. After these incubations the enzyme was found to be a mixture of functional and nonfunctional enzymes based on spectral changes with xanthine, on [14C]oxipurinol equilibration, and on steady-state kinetics. The 35S of [35S]thiosulfate was incorporated into desulfo xanthine oxidase in parallel with an increase in catalytic activity. Most of the 35S was cyanolysable but was protected from cyanolysis by pretreatment with allopurinol. The 35S was released from 35S-labeled reconstituted xanthine oxidase upon incubation with the rhodanese system containing unlabeled thiosulfate. However, catalytic activity remained unchanged, indicating that the sulfur atom was exchanged during the incubation.
43 citations
TL;DR: There was a significant increase in xanthine levels in patients with gout and renal failure, or renal failure on allopurinol, and plasma levels of oxipur inol were increased, but no correlation with glomerular filtration rate (GFR) was observed.
43 citations
TL;DR: In vivo, intragastric administration of Compound 1 was able to significantly reduce serum uric acid levels and inhibited hepatic xanthine oxidase activities of hyperuricemic mice in a dose-dependent manner and these results suggest thatcompound 1 is a novel competitive xanthines oxidase inhibitor and is worthy of further development.
43 citations
TL;DR: A group of substituted 5,8-quinolinequinones which exhibit antineoplastic activity and which are structurally related to the antitumor antibiotic streptonigrin induce single strand cleavage of PM2 covalently-closed circular-DNA (ccc-DNA) when reductively activated.
Abstract: A group of substituted 5,8-quinolinequinones which exhibit antineoplastic activity and which are structurally related to the antitumor antibiotic streptonigrin induce single strand cleavage of PM2 covalently-closed circular-DNA (ccc-DNA) when reductively activated. The cleavage which is detected by an ethidium fluorescence assay is specifically enhanced by cuprous and ferrous ion and is selectively inhibited by superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) and by free radical scavengers. Independent generation of the superoxide ion by xanthine – xanthine oxidase (EC 1.2.3.2) also cleaves PM2 DNA and therefore a chemical mechanism for the scission process induced by the streptonigrin analogues is formulated. A correlation between rate of PM2 ccc-DNA cleavage and inhibition of Walker carcinosarcoma 256 is observed.
43 citations