Hammerhead ribozymes: biochemical and chemical considerations

Ribozymes can be used to cleave specific mRNAs so as to prevent their translation. This presents an alternative to the use of antisense oligonucleotides for drug target validation or therapeutic purposes. The present review covers only one class of ribozymes, the hammerheads, which are small enough for chemical synthesis. Following an account of their structure and ability to catalyze the cleavage of target RNA is a discussion of some problems associated with their use as exogenous therapeutics. Chemical modifications that are used to address these issues are described.