Chigozie's Fun With Jolecule

Ribonuclease

            Ribonuclease is the enzyme that digests RNA. It is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonuclease is small, stable, and easily purified and has been an important enzyme in biochemical research. Ribonuclease can be divided into two groups: endoribonucleases and exoribonucleases. Endoribonucleases break down RNA from the middle through cleaving while exoribonucleases break down RNA from the 3’ or 5’ ends. Ribonuclease cleans cells of RNA that is no longer required and plays a key role in the maturing of RNA molecules such as messenger RNA and non-coding RNA. Also, ribonuclease acts as a first defense against RNA viruses and is the building block of more advanced immune strategies in cells. Because of ribonuclease’s nature to break down RNA, RNA in the cells has to be protected from ribonuclease. Defense mechanisms such as 5' end capping, 3'end polyadenylation, and folding within an RNA protein complex are implemented in cells. The alpha helices in this tertiary structure contain glycine which is the simplest amino acid with just an amino group, a carboxyl group and two hydrogen atoms. The glycine helps maintain structural alignment on the interior of ribonuclease as it breaks down RNA.

This is a close up on the tertiary structure of ribonuclease. Here one can see the alpha helices and the beta sheets that make up ribonuclease.

This is the catalytic part of the ribonuclease enzyme. Asp10, Glu48, Asp70, Asp134, and His124 can all be found in this area. These all contribute to catalysis in the enzyme by coordinating divalent metal ions that need to be present in order for the cleavage of RNA to be carried out. This would most likely be found in endoribonucleases.

This is a close up of an alpha helix in ribonuclease. This alpha helix contains glycine, which is important for the maintenance of structural alignment in ribonuclease. This glycine also adds to flexibility in this region.