Stefan Fusz

Publications (3)10.28 Total impact

• Source

  Available from: uni-bonn.de

  Article: Photocleavable initiator nucleotide substrates for an aldolase ribozyme.

  Stefan Fusz, Seergazhi G Srivatsan, Damian Ackermann, Michael Famulok
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  ABSTRACT: We have previously reported the in vitro selection of a ribozyme that catalyzes an aldol reaction between a levulinic amide aldol donor and a benzaldehyde substrate. The selection scheme involved the priming of the RNA library with a levulinic amide aldol donor group that was introduced via transcription priming in the presence of a modified guanosine mononucleotide derivative. Here we provide a detailed description of the synthesis of the ribozyme substrates and the substrate oligonucleotides used for its isolation and characterization. The aldol donor group was attached to the phosphate moiety of guanosine monophosphate via a photocleavable linker molecule. This initiator nucleotide was efficiently incorporated into RNA molecules of differing sizes and composition by transcription priming with T7 RNA polymerase. With this method modified RNA oligonucleotides as small as a 6-mer sequence can be generated. A temperature profile of the intermolecular reaction indicates that the modified RNA hexamer binds the ribozyme largely by Watson-Crick pairing and only to a minor extent via the non-RNA moiety, whereas the ribozyme appears to have evolved a specific binding site for the aldehyde substrate.
  The Journal of Organic Chemistry 08/2008; 73(13):5069-77. · 4.45 Impact Factor
• Source

  Available from: famuloklab.de

  Article: A ribozyme for the aldol reaction.

  Stefan Fusz, Alexander Eisenführ, Seergazhi G Srivatsan, Alexander Heckel, Michael Famulok
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  ABSTRACT: Directed in vitro evolution can create RNA catalysts for a variety of organic reactions, supporting the "RNA world" hypothesis, which proposes that metabolic transformations in early life were catalyzed by RNA molecules rather than proteins. Among the most fundamental carbon-carbon bond-forming reactions in nature is the aldol reaction, mainly catalyzed by aldolases that utilize either an enamine mechanism (class I) or a Zn(2+) cofactor (class II). We report on isolation of a Zn(2+)-dependent ribozyme that catalyzes an aldol reaction at its own modified 5' end with a 4300-fold rate enhancement over the uncatalyzed background reaction. The ribozyme can also act as an intermolecular catalyst that transfers a biotinylated benzaldehyde derivative to the aldol donor substrate, coupled to an external hexameric RNA oligonucleotide, supporting the existence of RNA-originated biosynthetic pathways for metabolic sugar precursors and other biomolecules.
  Chemistry & Biology 09/2005; 12(8):941-50. · 5.83 Impact Factor
• Article: A Zwitterionic Phosphonio‐1, 2, 4‐Diazaphospholide and Neutral 1, 2, 4‐Diazaphosphole — A Comparative Study of Molecular Structures and Co‐ordination Properties

  Laszlo Szarvas, Zoltan Bajko, Stefan Fusz, Sebastian Burck, Jörg Daniels, Martin Nieger, Dietrich Gudat Professor Dr
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  ABSTRACT: The bis-phosphonio-1, 2, 4-diazaphospholide salt (1[Cl]) reacts with complex boron hydrides under selective extrusion of one PPh3 moiety to give borane adducts of a novel zwitterionic phosphonio-1, 2, 4-diazaphospholide. Both the Et3B adduct 2b and the free zwitterionic heterocycle 3, which was liberated by further reaction of 2b with NEt3, were characterized by spectroscopic data and 2b, as well, by a single crystal X-ray diffraction study. The comparison of the structural data with those of a neutral 1, 2, 4-diazaphosphole and a lithium-1, 2, 4-diazaphospholide which was formed by deprotonation of the parent 1, 2, 4-diazaphosphole 4a discloses trends in endocyclic bonding distances which can be rationalized in terms of a charge dependent shift in the π-electron distribution. First studies of the co-ordination properties reveal for both 2b and 4a a marked preference to bind two M(CO)5-fragments (M = Cr, W) via the lone-pairs of the phosphorus and one nitrogen atom; mononuclear complexes with P-co-ordinated heterocycles are formed as intermediates. A single crystal X-ray diffraction study of the dinuclear complex [Cr2(CO)10(μ2-C2H3N2P-κP, κN)] (10a) together with spectroscopic studies (including 183W NMR studies of tungsten complexes) suggests that M→L back donation is more efficient for P- than for N-bound metal fragments. No evidence for π-co-ordination of the 1, 2, 4-diazaphosphole ring to a Cr(CO)3 fragment was obtained.Ein Zwitterionisches Phosphonio-1, 2, 4-Diazaphospholid und Neutrales 1, 2, 4-Diazaphosphol — Eine Vergleichende Studie von Molekülstrukturen und KoordinationseigenschaftenDas Bis-phosphonio-1, 2, 4-diazaphospholid-Salz (1[Cl]) reagiert mit komplexen Borhydriden unter selektiver Abspaltung einer PPh3-Gruppe zu Boranaddukten eines neuen zwitterionischen Phosphonio-1, 2, 4-diazaphospholids. Sowohl das Et3B-Addukt 2b als auch der freie zwitterionische Heterocyclus 3, der durch weitere Reaktion von 2b mit NEt3 freigesetzt wurde, wurden durch spektroskopische Daten und 2b zusätzlich durch eine Einkristall-Röntgenstrukturanalyse charakterisiert. Der Vergleich der Strukturdaten mit denen eines neutralen 1, 2, 4-Diazaphosphols und eines Lithium-1, 2, 4-diazaphospholids, das durch Deprotonierung der Stammverbindung 1, 2, 4-Diazaphosphol 4a erhalten wurde, zeigen Trends in den endocyclischen Bindungslängen, die im Sinne ladungsabhängiger Variationen der π-Elektronenverteilung rationalisiert werden können. Erste Studien der Koordinationseigenschaften zeigen sowohl für 2b als auch 4a eine deutliche Präferenz zur Bindung von zwei M(CO)5-Fragmenten (M = Cr, W) über die freien Elektronenpaare des Phosphor- und eines Stickstoffatoms; einkernige Komplexe mit P-koordinierten Heterocyclen entstehen als Zwischenstufen. Eine Einkristall-Röntgenstrukturanalyse des zweikernigen Komplexes [Cr2(CO)10(μ2-C2H3N2P-κP, κN)] (10a) in Verbindung mit spektroskopischen Untersuchungen (einschließlich 183W NMR Untersuchungen der Wolframkomplexe) geben Hinweise für eine effizientere M°L Rückbindung von P- im Vergleich zu N-gebundenen Metallfragmenten. Anzeichen für eine π-Koordination des 1, 2, 4-Diazaphospholrings an ein Cr(CO)3-Fragment wurden nicht erhalten.
  Zeitschrift für anorganische Chemie 10/2002; 628(11):2303 - 2310.