Ribozymes, Deoxyribozymes and Ribosomes

Ribozymes and deoxyribozymes are RNA and DNA molecules with endonuclease catalytic activity and were probably evolutionary forerunners of enzymes. A variety of ribozymes have been discovered, such as the hammerhead ribozyme, which is one of the smallest ribozymes that can catalyse the site-specific hydrolysis of a phosphodiester bond in RNA. Although described as hydrolysis , the autocatalytic reaction does not involve water; rather, the cleavage reaction is an isomerisation rearrangement of phosphodiester bonds in the RNA.
Production of these new biological catalysts, which can be tailored to suit a specific biotransformation, is a major development that has the potential to increase the usefulness of biological catalysts. The biocatalysts currently available for development are those existing in Nature and applications evolve around the existing set of biocatalysts. New applications will be possible if bespoke biocatalysts can be designed to suit an application. Ribozymes have attracted great attention because comparative studies of the properties of enzymes and ribozymes can provide new fundamental information on the chemical/physical principles of biological catalysis.6 Ribozymes also recognise their target substrate (RNA) in a highly sequence-specific manner and this degree of specificity should permit the development of important therapeutic applications for both inherited and acquired diseases.For example, ribozymes may be used to counteract harmful gene expression by attacking gene products (mRNA) produced by faulty, damaged or uncontrolled genes. Such targets might be the mRNA produced by oncogenes (cancer) and viral genomes from human immunodeficiency virus type 1(HIV-1).
In another area of development, a 49 nucleotide long ribozyme has been immobilised on an agarose support material and used to catalyse formation of C–C bonds in a Diels–Alder reaction, which is one of the most important C–C bond formation reactions used by organic chemists. An important point with this development is that a number of limitations imposed by protein-based enzymes that catalyse these reactions can be overcome using a ribozyme.
Ribosomes have been known for a long time as the structures in cells that are responsible for protein synthesis. Recent studies on bacterial ribosomes have revealed that the active site of a ribosome where the peptide bond is formed between two amino acids is composed of RNA. Thus although a ribosome is a complex multi-component ribonucleotide and protein structure; it has a ribozyme at its core active site.