Document 0907
 DOCN  M9440907
 TI    High activity and stability of hammerhead ribozymes containing
       2'-modified pyrimidine nucleosides and phosphorothioates.
 DT    9404
 AU    Heidenreich O; Benseler F; Fahrenholz A; Eckstein F; Max-Planck-Institut
       fur Experimentelle Medizin, Gottingen,; Federal Republic of Germany.
 SO    J Biol Chem. 1994 Jan 21;269(3):2131-8. Unique Identifier : AIDSLINE
       MED/94124569
 AB    The influence of chemical modifications on the catalytic activity and
       stability of a hammerhead ribozyme directed against the long terminal
       repeat RNA of the human immunodeficiency virus 1 was examined. Previous
       studies had shown that substitution of all pyrimidine nucleosides by
       their 2'-fluoro analogs led to an 8-fold decrease in catalytic
       efficiency in the cleavage reaction compared to the unmodified ribozyme
       (Heidenreich, O., and Eckstein, F. (1992) J. Biol. Chem. 267,
       1904-1909). It is shown here that replacement of the
       2'-fluoro-2'-deoxyuridines in the conserved region of this ribozyme,
       positions 4 and 7, by 2'-amino-2'-deoxyuridines fully restores catalytic
       activity of the ribozyme. Ribozymes containing these 2'-modifications
       show an increased stability against RNases present in fetal calf serum
       and in cell culture supernatant. The stability is increased further by
       the incorporation of four terminal phosphorothioates as protection
       against 3'-exonucleases, the degree of which depends on the secondary
       structure of the ribozyme. Such ribozymes are stable in undiluted fetal
       calf serum for at least 24 h. The results clearly demonstrate the
       potential to design stable ribozymes without any loss of catalytic
       activity.
 DE    Animal  Base Sequence  Cattle  Enzyme Stability  *HIV Long Terminal
       Repeat  HIV-1/GENETICS  Kinetics  Molecular Sequence Data  Nucleic Acid
       Conformation  Pyrimidine Nucleosides/*METABOLISM  Ribonucleases/BLOOD
       RNA, Catalytic/*CHEMISTRY/*METABOLISM  Support, Non-U.S. Gov't
       Thionucleotides/*METABOLISM  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).