Ribozyme

Ribozyme (from ribonucleic acid ( RNA), and enzyme) are catalytically active RNA molecules, such as enzymes which catalyze chemical reactions.

For this discovery Sidney Altman and Thomas R. Cech were awarded the 1989 Nobel Prize in Chemistry, as had been assumed up to this point, that in the cell only proteins have catalytic activity. Far-reaching implications of the discovery of ribozymes, especially in the field of chemical evolution, since it supports the hypothesis that the RNA world.

However, ribozymes are not uncommon, each cell contains several thousand of them, in about a dozen classes, which differ structurally. So, for example, catalyzes the 23S rRNA of the ribosome, the formation of the peptide bond during translation ( peptidyl ). The spliceosomes are ribozymes, here catalyzes the close network of splicing snRNAs. Both the ribosome and in the spliceosome, there are also proteins; these take but in the actual reaction does not participate, but make only that the RNA occupies the right structure for catalysis. There are also ribozymes that display without the need proteins, such as the hammerhead ribozyme, for example, take advantage of some viruses to - to put it vividly - to cut their RNA to the correct length, or the selbstspleißende intron from Tetrahymena thermophila, for the discovery of the above-mentioned Nobel prize. Several classes of ribozymes intersect themselves in the final functional form ("self - cleaving ").

In the test tube a number of ribozymes further developed ( mostly by SELEX ), which catalyze various reactions. The main difference between enzymes and ribozymes lies in the reaction rate but not in the diversity of catalyzed reactions. Particularly interesting is currently the catalysis of a Diels -Alder reaction, since they could have served principally to the very early stage of evolution to create more blocks for RNAs. A big step so to an RNA that synthesizes their own blocks and replicates itself - a possible origin of life with a transition from a chemical into a busy evolution.