Uridine diphosphoglucose (UDPG) has been shown to have tissue-specific effects that have proved to be of clinical value in the treatment of some liver ailments. In an effort to determine something about the mechanism of action, we investigated the effect of UDPG on the levels of 5-phosphoribosyl pyrophosphate (PRPP) and PRPP synthetase in mouse liver, spleen and transplanted tumors. Three strains of mice were studied with and without tumors under various experimental conditions. Balb/c mice were infused with UDPG intraperitoneally at levels of 0.16 g/kg/day (0.28 mmole) to 1.6 g/kg/day (2.8 mmoles) for 5 days. At the low dose rate the PRPP level in the liver was found to increase 3-fold. A slight increase was noted in the activity of PRPP synthetase. However, when the UDPG was infused at a level of 2.8 mmoles/kg/day, the increases in both the synthetase and PRPP were inhibited. Both CRF1 and CD8 mice were less sensitive to the effects of UDPG per se. However, the high level of PRPP in the tumors they carried was greatly affected by the UDPG infusion. The tumor-specific inhibition of PRPP suggests that this action might prove to be useful combination therapy with inhibitors of purine and pyrimidine nucleotide synthesis in various rescue regimens. UDPG was found to enter cells intact before it was cleaved into glucose phosphate and UMP. The fact that UDPG was also found in the membrane fraction suggests that either there is a specific transport mechanism or UDPG exerts its action via interaction with the cell membrane.

Sealed and unsealed plasma membrane vesicles were prepared from human erythrocytes and lymphocytes. Phosphoribosylpyrophosphate synthetase (PRibPP synthetase), hypoxanthine phosphoribosyltransferase (HPRTase), and adenine phosphoribosyltransferase (APRTase) activities are detectable on both inside-out and right-side-out sealed vesicles. Ghost preparations were about 0.2%, 1%, and 1.2% of the total erythrocyte and 0.5%, 5.3%, and 9.7% of the lymphocyte APRTase, HPRTase, and PRibPP synthetase activities. The rapid decrease in these enzyme activities, upon further purification of the membranes, seemed to suggest that they might be loosely bound extrinsic proteins. Evidence confirming the localization of these enzymes on the cell surface was obtained by measuring production of [14C]AMP by intact cells in medium containing [14C]adenine, ribose 5-phosphate, and Mg2+ATP. The formation of AMP was linear with time and number of cells present. Magnesium and phosphate exerted different effects on the production of extracellular AMP than on intracellular, which involves transport as well as phosphoribosylation. Cytosoluble and membrane-bound APRTase and PRibPP synthetase exhibited different catalytic properties and sensitivities to effectors. Membranes of erythrocytes of HPRTase-deficient patients contain little or no HPRTase activity when assayed in the absence of Triton. Reisolation of these membranes from admixture with normal hemolysates did not result in any bound activity; thus, the membrane-bound activity is not an artifact of the isolation procedure. Lysis with Triton released activity equal to about half that of control membranes. This is further evidence that the enzyme is firmly bound to the membrane.

Reduction of 4(5)-nitroimidazole-5(4)-sulfonamide afforded the sulfonamide analogue of 4(5)-aminoimidazole-5(4)-carboxamide (AICA). This was formylated to afford the sulfonamide analogue of formyl-AICA and was ring closed to the unsubstituted 6-sulfonyl analogue of guanine, 3-aminoimidazo[4,5-e]-1,2,4-thiadizine 1,1-dioxide. Diazotiz ation of the latter afforded the corresponding 6-sulfonyl analogue of xanthine. None of the imidazole-sulfonamides or the purine 6-sulfonyl analogues inhibited the growth of L1210 cells in culture nor were they substrates for or significant inhibitors of human hypoxanthine--guanine phosphoribosyltransferase or milk xanthine oxidase.

5-Phosphoribosyl 1-pyrophosphate synthetase (PRibPP synthetase EC 2.7.6.1) isolated from rat intestinal mucosa was found to be membrane associated. The subcellular distribution of PRibPP synthetase activity seems to parallel that of gamma-glutamyl transpeptidase, indicating it to be in the brush border. The tip cells of rat intestinal mucosa were richer in PRibPP synthetase than the crypt cells. Chromatography of a Triton-solubilized particulate fraction unmasked a peak of hypoxanthine phosphoribosyltransferase activity that was not detectable before. The activity, too, was concentrated in the brush border. The coexistence of these two activities in the fraction of the bowl involved in absorption has led to the suggestin that the synthetase and phosphoribosyl-transferase are part of a coupled transport system.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyamine-polyphosphate complexes as enzyme inhibitorsLily C. Yip and M. Earl BalisCite this: Biochemistry 1980, 19, 9, 1849–1856Publication Date (Print):April 1, 1980Publication History Published online1 May 2002Published inissue 1 April 1980https://doi.org/10.1021/bi00550a019RIGHTS & PERMISSIONSArticle Views94Altmetric-Citations14LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (946 KB) Get e-Alerts Get e-Alerts

It has been reported from these laboratories that of 425 patients with gouty arthritis, uric acid stones or both, hypoxanthine guanine phosphoribosyltransferase (HPRTase) was deficient in only 1.6% of the cases, including five members of one family (1). This result, together with others, indicates that HPRTase deficiency per se is a rather uncommon cause of gout. We have also shown that correlation of symptomatology with the amount of residual HPRTase activity as in erythrocytes is not always good. In some instances, HPRTase activity has been extremely low, as in Lesch-Nyhan (L-N) disease, and yet the patients have been normal neurologically (2).

Upon storage, human erythrocyte phosphoribosyl pyrophosphate synthetase (PRibPP synthetase, EC 2.7.6.1) from normal individuals was found to undergo a spontaneous dissociation into active enzyme components of much smaller molecular mass (60 000--90 000). These modified forms of enzyme exhibit kinetic properties different from the original large molecular weight enzyme (over 200 000). The small active components can be reversibly associated to form larger molecules in the presence of purine ribonucleotides as well as phosphoribosyl pyrophosphate (PRibPP). ATP was found to be most effective in associating PRibPP synthetase, while guanylate nucleotides seem to have no effect. The large molecular weight components, once separated from the milieu, were not able to undergo further dissociation. Fresh or stored human white cell tissue homogenates were found to lack the low-molecular-weight enzyme under all our experimental conditions. A characteristic enzyme modification similar to that observed in stored erythrocyte was also noted in erythrocytes of increasing ages. The physiological significance of these findings to the regulatory function of PRibPP synthetase in purine metabolism in vivo is discussed.

Gilles de la Tourette syndrome is a neurologic disorder in which there are both motor and behavioral abnormalities, approximately 75 per cent of the patients are male and the onset of the disease is usually between two and 14 years of age.1 , 2 Recently, a genetic origin has been suggested on the basis of an approximate 10 per cent family history of the disease,2 , 3 with numerous reports describing both parent and offspring with the syndrome4 , 5 and a high rate in Ashkenazic Jews and a low rate in the black population. The initial symptom is usually involuntary ticlike muscle movements. With progression . . .

Arthritis & RheumatismVolume 18, Issue S1 p. 695-698 ArticleFree to Read Overproduction of uric acid in primary gout Ts'Ai-Fan Ÿ MD, Ts'Ai-Fan Ÿ MD Research Professor of Medicine, Mount Sinai School of Medicine, City University of New York Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this authorM. Earl Balis PhD, M. Earl Balis PhD Professor of Biochemistry, Cornell University Graduate School of Medical Sciences, and member, Sloan Kettering Memorial Cancer Center Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this authorLily C. Yip PhD, Lily C. Yip PhD Assistant Professor of Biochemistry, Cornell University Graduate School of Medical Sciences, and Associate, Sloan Kettering Memorial Cancer Center Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this author Ts'Ai-Fan Ÿ MD, Ts'Ai-Fan Ÿ MD Research Professor of Medicine, Mount Sinai School of Medicine, City University of New York Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this authorM. Earl Balis PhD, M. Earl Balis PhD Professor of Biochemistry, Cornell University Graduate School of Medical Sciences, and member, Sloan Kettering Memorial Cancer Center Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this authorLily C. Yip PhD, Lily C. Yip PhD Assistant Professor of Biochemistry, Cornell University Graduate School of Medical Sciences, and Associate, Sloan Kettering Memorial Cancer Center Mount Sinai School of Medicine, Cornell University Graduate School of Medical Sciences, and Sloan-Kettering Memorial Cancer Center, New York, New York.Search for more papers by this author First published: November/December 1975 https://doi.org/10.1002/art.1780180709Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume18, IssueS1November/December 1975Pages 695-698 RelatedInformation

Preassay-incubation of the highly purified human erythrocyte adenine phosphoribosyltransferase (EC 2.4.2.7) (AMP pyrophosphorylase) with one of its substrates, 5-phosphoribosyl 1-pyrophosphate (PRibPP), changes the apparent V max value of the enzyme reaction. The extent of inhibition by preassay-incubation with an inhibitor, fructose 1,6-diphosphate (FDP), or a destabilizer, hypoxanthine (Hx), is found not to be proportional to the amount of the inhibitor present. The maximum inhibition achieved by preassay-incubation was about 40%. The PRibPP, FDP, and Hx induced changes in AMP pyrophosphorylase do not require the presence of divalent ions. The inhibtion of AMP pyrophosphorylase produced by preincubation with Hx was prevented when PRibPP was added to the preassay-incubation system. However, the preassay-incubation effect of FDP was only partially diminished under the same conditions. Contrary to the PRibPP-bound AMP pyrophosphorylase, the adenine-bound enzyme was found to be more heat labile than the unbound enzyme. Similar thermal instability was also observed with FDP- and Hx-bound enzyme. Our experimental results indicate that a conformational change of AMP pyrophosphorylase induced by the binding of metabolites is a slow process as compared to the overall catalytic reaction. This hysteretic characteristic of AMP pyrophosphorylase may be one of the regulatory mechanisms in purine intermediary metabolism.

The effect of 2,3-diphosphoglycerate (2,3-DPG) upon three partially purified enzymes from human erythrocytes, 5-phosphoribosyl-l-pyrophosphate synthetase (PRibPP synthetase, E.C.2.7.6.1), IMP:pyrophosphate phosphoribosyltransferase (E.C.2.4.2.8 HPRibTase) and AMP:pyrophosphate phosphoribosyltransferase (E.C.2.4.2.7 APRibTase) has been studied kinetically. PRibPP synthetase was not greatly inhibited at physiologic concentrations of 2,3-DPG at optimal phosphate concentration, but it was inhibited appreciably by 2,3-DPG at physiologic phosphate levels. Both HPRibTase and APRibTase were inhibited by 2,3-DPG at its normal intracellular concentration. 2,3-DPG is a competitive inhibitor with respect to the substrates, ribose-5-phosphate and 5-phosphoribosyl-l-pyrophosphate. The Ki values for these inhibitions are given and the possible physiologic significance of these findings are discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAge-induced changes in adenosine monophosphate:pyrophosphate phosphoribosyltransferase and inosine monophosphate:pyrophosphate phosphoribosyltransferase from normal and Lesch-Nyhan erythrocytesLily C. Yip, Joseph Dancis, Bonnie Mathieson, and M. Earl BalisCite this: Biochemistry 1974, 13, 12, 2558–2561Publication Date (Print):June 1, 1974Publication History Published online1 May 2002Published inissue 1 June 1974https://pubs.acs.org/doi/10.1021/bi00709a013https://doi.org/10.1021/bi00709a013research-articleACS PublicationsRequest reuse permissionsArticle Views17Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Phytohemagglutinin (PHA) markedly stimulates 3H-hypoxanthine incorporation by lymphocytes of normal subjects as revealed by radioautography. There is no corresponding increase in activity of hypoxanthine phosphoribosyltransferase (HPRT) in lysates but the level of phosphoribosylpyrophosphate (PRPP), the cosubstrate for the reaction, is higher. Lymphocytes from a patient with partial HPRT deficiency responded to PHA as did the normals, whereas the response in Lesch-Nyhan (LN) subjects was variable. PHA-stimulated lymphocytes from two LN patients showed some increase in 3H-hypoxanthine incorporation, while two others failed to respond. The observations provide further evidence of genetic heterogeneity among LN patients.

Several genetic defects have been recognized which have presented different levels of residual IMP pyrophosphorylase (HPRTase) activity and concomitant modifications of the clinical manifestations. The most extreme is Lesch-Nyhan disease with little or no detectable enzyme in the red cells and severe neurological damage.1 If the enzyme deficiency is less complete, there may be only overproduction of uric acid and gout.

A family is reported in which each of two sisters has a son with no detectable hypoxanthine phosphoribosyltransferase (HPRT) (EC 2. 4. 2. 8) in his erythrocytes, a finding considered pathognomonic of Lesch-Nyhan disease. However, neither has the stigmata of the disease. One boy is neurologically normal, and the other is moderately retarded. There was only a slight increase in urinary uric acid, but the amounts of hypoxanthine and xanthine, and their ratios, were similar to those found in Lesch-Nyhan disease, strongly indicating that excesses of these last two oxypurines are not responsible for the symptomatology in that disease. In contrast to the nondetectable HPRT activity in the red blood cells, leukocyte lysates from the two boys have 10-15% of normal activity, possibly reflecting continuing synthesis of an unstable enzyme. This hypothesis is supported by the demonstration that at 4 degrees C HPRT activity was rapidly lost in the propositus while the activity increased in control subjects. The mother's cells were intermediate between the two. The intact and disrupted leukocytes of the hemizygote, in the absence of added phosphoribosyl converted as much hypoxanthine to inosinate as the normal cell, and appropriate tests indicated that under these circumstances enzyme concentration is not rate limiting whereas the concentration of the cosubstrate, phosphoribosyl pyrophosphate, is. The capacity for normal function in the intact mutant cell is more representative of in vivo conditions than the lysate, which may explain the important modification of clinical symptomatology, the relatively mild hyperuricosuria, and the presence of mosaicism in the circulating blood cells of the heterozygotes. A similar explanation may apply to other genetic diseases in which incomplete but severe enzyme deficiencies are found in clinically normal individuals. An associated deficiency in glucose-6-phosphate dehydrogenase in this family permitted confirmation of previous observations on linkage with hypoxanthine phosphoribosyltransferase.