The biosynthesis of 6-azauracil riboside byEscherichia coli growing in the presence of 6-azauracil

Zusammenfassung Bei der Kultivierung vonE. coli in 6-azaurazilhaltigem Medium wird ein neuer Stoff akkumuliert, der als 6-Azaurazilribosid identifiziert wurde.     

The anti-tumour activity of 6-azauracil riboside

Zusammenfassung Es wird die cancerostatische Wirkung des 6-Azauracilribosids auf die subkutane Form des Ehrlich-Aszites-Tumors beschrieben und festgestellt, dass 6-Azauracilribosid ungefähr 6mal wirksamer ist als 6-Azauracil.     

Plastid differentiation on 6-azauracil media

Résumé Les mutants au locusm de l'Arabidopsis ne réussissent pas à former de chloroplastes normaux dans certaines conditions et montrent des activités plus hautes en synthèse de pyrimidines que le témoin. La nutrition aseptique par 6-azauracile, inhibiteur spécifique de cette voie métabolique, restaure la différenciatin de structure lamellaire dans la plupart de ces organites, mais aux concentrations élevées, apparaissent des chloroplastes morphologiquement déviants, quoique de fonction efficace.     

Inhibition ofSaccharomyces cerevisiae division by 5-trifluoro-methyl-6-azauracil

Summary Cell division, as studied in asynchronous cultures of yeast cells, is sensitive to 5-trifluoromethyl-6-azauracil (F₃CAzU). Under defined conditions (10 mmoles l^–1 F₃CAzU) this compound blocks immediately and completely the process of cell division. Using synchronized cells, the time-point at which division process of yeast cell can be inhibited by F₃CAzU has been determined. The inhibitor effect of this compound is completely reversed by thymine, thymidine and uracil.     

The inhibitory effect of 6-azauracil riboside on the multiplication of vaccinia virus

Zusammenfassung Die Hemmwirkung von 6-Azauracilribosid auf die Vermehrung des Vaccina-Virus in Gewebekulturen wurde festgestellt. Die Substanz blieb gegen andere Viren (Influenza A, NDV, EEE) wirkungslos.     

The anticancerous action of 6-azauracil (3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine)

Zusammenfassung Es wurde die kanzerostatische Wirkung des 6-Azauracils auf den Ehrlich-Aszites-Tumor beschrieben und mit der Wirkung des 6-Mercaptopurins verglichen.     

Inhibitory effect of 5-bromo-6-azauracil on growth and cell division ofSaccharomyces cerevisiae

Summary The most marked effect of 5-bromo-6-azauracil (BrAzU) on yeast cells is to cause cell lysis. The inhibition of the lytic process is delayed and this delay coincides in time with the capacity of preformed pyrimidines to reverse the effect of BrAzU.     

Synthesis of 6-deoxy-6-fluoro-L-ascorbic acid

Summary 6-Deoxy-6-fluoro-L-ascorbic acid has been synthesized in 5 steps starting from 2,3-4,6-di-O-isopropylidene-2-keto-L-gulonic acid.Dedicated to Professor Albert Szent-Györgyi, National Foundation for Cancer Research, Marine Biological Laboratory, Woods Hole, Massachusetts, on the occasion of his 85th birthday.     

G-6PD loading of G-6PD-deficient erythrocytes

G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.     

G-6PD loading of G-6PD-deficient erythrocytes

Summary G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.     

Regulation of Lrp6 phosphorylation

The Wnt/β-catenin signaling pathway plays important roles in embryonic development and tissue homeostasis, and is implicated in human disease. Wnts transduce signals via transmembrane receptors of the Frizzled (Fzd/Fz) family and the low density lipoprotein receptor-related protein 5/6 (Lrp5/6). A key mechanism in their signal transduction is that Wnts induce Lrp6 signalosomes, which become phosphorylated at multiple conserved sites, notably at PPSPXS motifs. Lrp6 phosphorylation is crucial to β-catenin stabilization and pathway activation by promoting Axin and Gsk3 recruitment to phosphorylated sites. Here, we summarize how proline-directed kinases (Gsk3, PKA, Pftk1, Grk5/6) and non-proline-directed kinases (CK1 family) act upon Lrp6, how the phosphorylation is regulated by ligand binding and mitosis, and how Lrp6 phosphorylation leads to β-catenin stabilization.     

Hydroxylation of demethoxy-Q6 constitutes a control point in yeast coenzyme Q6 biosynthesis

Coenzyme Q is a lipid molecule required for respiration and antioxidant protection. Q biosynthesis in Saccharomyces cerevisiae requires nine proteins (Coq1p–Coq9p). We demonstrate in this study that Q levels are modulated during growth by its conversion from demethoxy-Q (DMQ), a late intermediate. Similar conversion was produced when cells were subjected to oxidative stress conditions. Changes in Q₆/DMQ₆ ratio were accompanied by changes in COQ7 gene mRNA levels encoding the protein responsible for the DMQ hydroxylation, the penultimate step in Q biosynthesis pathway. Yeast coq null mutant failed to accumulate any Q late biosynthetic intermediate. However, in coq7 mutants the addition of exogenous Q produces the DMQ synthesis. Similar effect was produced by over-expressing ABC1/COQ8. These results support the existence of a biosynthetic complex that allows the DMQ₆ accumulation and suggest that Coq7p is a control point for the Q biosynthesis regulation in yeast. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 04 September 2008; received after revision 22 October 2008; accepted 23 October 2008     

Potentiation of the inhibition of xanthine oxidase by a combination of 6-mercaptopurine and 6-thioguanine

Summary Carcinostatic agents, 6-mercaptopurine and 6-thioguanine inhibited the in vitro and in vivo activity of the enzyme xanthine oxidase (xanthine-oxygen oxidoreductase E.C. 1.2.3.2.). Simultaneous, addition of a mixture of the 2 antimetabolites produced a synergistic effect on the inhibition of the enzyme activity.We thank the University Grants Commission, New Delhi, for their financial assistance and the Dean, M.G.M. Medical College Indore, for providing necessary facilities.     

Isolation of 6-hydroxymethyl-eugenin fromChaetomium minutum

Zusammenfassung 6-Hydroxymethyl-eugenin (1) wurde als Nebenprodukt von Chaetocin aus dem PilzstammChaetomium minutum isoliert. Eugenin und Eugenitin, die Inhaltsstoffe der NelkeEugenia caryophyllata, Leprariasäure aus verschiedenen Flechten, sowie der Pilzmetabolit1 unterscheiden sich nur in Stellung 6 des Chromongerüstes.     

Reaction of 6-aminopenicillanic acid with frequentin

Zusammenfassung 6-Aminopenizillansäure setzt sich mit Frequentin, einem Schimmelmetaboliten, unter gewissen Temperatur- und pH-Bedingungen um. Der entstandene Komplex stellt wahrscheinlich eine Tautomerenmischung aus Enamin und Enolimin dar, die beide durch Wasserstoffbrücken stabilisiert werden.     

Production of 6-methoxy-mellein bySporormia bipartis Cain

Zusammenfassung Die Isolierung von 6-Methoxymellein I (R=OCH₃) aus Submerskulturen vonSporormia bipartis Cain wird beschrieben.