title: Brief communication: stability and catalytic activity of novel circular DNAzymes.
abstract: DNAzymes represent a new generation of catalytic nucleic acids for specific RNA targeting in order to inhibit protein translation from the specifically cleaved mRNA. The 10-23 DNAzyme was found to hydrolyze RNA in a sequence-specific manner both in vitro and in vivo. Although single-stranded DNAzymes may represent the most effective nucleic acid drug to date, they are nevertheless sensitive to nuclease degradation and require modifications for in vivo application. However, previously used stabilization of DNAzymes by site-specific phosphorothioate (PT) modifications reduces the catalytic activity, and the PTO displays toxic side effects when applied in vivo. Thus, improving the stability of DNAzymes without reducing their catalytic activity is essential if the potential of these compounds should be realized in vivo.
  
  
  RESULTS
  The Circozyme was tested targeting the mRNA of the most common genetic rearrangement in pediatric acute lymphoblastic leukemia TEL/AML1 (ETV6/RUNX1). The Circozyme exhibits a stability comparable to PTO-modified DNAzymes without reduction of catalytic activity and specificity and may represent a promising tool for DNAzyme in vivo applications.
  
  
  CONCLUSIONS
  The inclusion of the catalytic site and the specific mRNA binding sequence of the DNAzyme into a circular loop-stem-loop structure (Circozyme) of approximately 70 bases presented here represents a new effective possibility of DNAzyme stabilization.
authors.affiliation: Charité Universitätsmedizin Berlin, Otto-Heubner Center for Pediatric and Adolescent Medicine (OHC), Department of Pediatric Oncology/Hematology, Berlin, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Seifert
authors.forename: Tillmann
authors.initials: T
authors.lastname: Taube
authors.forename: Kriztina
authors.initials: K
authors.lastname: Paal
authors.forename: Hagen Graf
authors.initials: HG
authors.lastname: von Einsiedel
authors.forename: Sven
authors.initials: S
authors.lastname: Wellmann
authors.forename: Günter
authors.initials: G
authors.lastname: Henze
authors.forename: Karl
authors.initials: K
authors.lastname: Seeger
authors.forename: Matthias
authors.initials: M
authors.lastname: Schroff
authors.forename: Burghardt
authors.initials: B
authors.lastname: Wittig
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics*; D021881:DNA, Catalytic / Q000737:chemistry* / Q000378:metabolism; D004270:DNA, Circular / Q000737:chemistry* / Q000378:metabolism; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000097764:ETS Translocation Variant 6 Protein
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D021881:DNA, Catalytic; D004270:DNA, Circular; D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger; C102421:TEL-AML1 fusion protein; D000097764:ETS Translocation Variant 6 Protein