       Document 0091
 DOCN  M9640091
 TI    Ribozymes: from mechanistic studies to applications in vivo.
 DT    9604
 AU    Ohkawa J; Koguma T; Kohda T; Taira K; National Institute of Bioscience
       and Human Technology, Agency of; Industrial Science & Technology, MITI.
 SO    J Biochem (Tokyo). 1995 Aug;118(2):251-8. Unique Identifier : AIDSLINE
       MED/96064140
 AB    The hammerhead ribozyme belongs to the class of molecules known as
       antisense RNAs. However, because of short extra sequences that form the
       so-called catalytic loop, it can act as an enzyme. Since the catalytic
       domain captures magnesium ions and magnesium ions can cleave
       phosphodiester bonds, hammerhead ribozymes are recognized as
       metalloenzymes. In general, the cleavage of phosphodiester bonds
       involves acid/base catalysis, with proton transfer occurring in the
       transition state. When the possibility of such a proton-transfer process
       was examined by measuring solvent isotope effects, it became apparent
       that no proton transfer occurs in the transition state during reactions
       catalyzed by a hammerhead ribozyme. It is likely, therefore, that
       hammerhead ribozymes exploit the general double-metal-ion mechanism of
       catalysis, with Mg2+ ions coordinating directly with the attacking and
       leaving oxygen moieties. Since the hammerhead ribozyme is one of the
       smallest RNA enzymes known and has potential as an antiviral agent, thus
       ribozyme has been extensively investigated for applications in vivo.
       Ribozymes are described that have possible utility as agents against
       HIV-1.
 DE    Animal  Base Sequence  Gene Expression  Human  Hydrolysis  Molecular
       Sequence Data  Nucleic Acid Conformation  RNA,
       Catalytic/CHEMISTRY/GENETICS/*METABOLISM/THERAPEUTIC USE  Substrate
       Specificity  JOURNAL ARTICLE  REVIEW  REVIEW, TUTORIAL

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

