The Ca~(2+) Ion as a Cofactor for a Novel RNA-Cleaving Deoxyribozyme

摘要

The structure and reactivity of ribozymes and proteins depend on specific interactions of their monomers with each other, and in the end it is their primary sequence that determines their secondary and tertiary structure. However, the ionic strengthof the buffer solution and the presence of certain divalent metal ions are often crucial for the formation of stable and active structures. This is particularly true for ribozymes, for which Mg~(2+) or Mn~(2+) ions are commonly used as cofactors for catalysis. These ions are directly involved in the reaction by activating functional groups or water and cannot be substituted by other polycations. Therefore, ribozymes are a special class of metalloenzymes; no known ribozyme is active in the absence of divalent metal ions, which are thus essential for their chemistry. In principle, one can think of RNA as a scaffold for a site-specific reaction of the metal ion.