Sandbox Reserved 200: Difference between revisions

Bovine pancreatic ribonuclease A [http://en.wikipedia.org/wiki/Ribonuclease_A (RNase A)] is an enzyme that catalyzes the hydrolysis of RNA through [http://www.proteopedia.org/wiki/index.php/Sandbox_Reserved_193 acid-base catalysis].  RNase A has the capability to structurally form dimers, trimers, tetramers, and pentamers based on the structure of the [http://www.proteopedia.org/wiki/index.php/Sandbox_Reserved_192 RNase A monomer].  Though there are many oligomers, the three-dimensional structure for only the major dimer, minor dimer, and minor trimer are known.  Unlike the monomers, all the oligomers are capable of catalyzing the hydrolysis of double stranded RNA (dsRNA).<ref name="tumor">PMID:12697760</ref>  The oligomers are formed by 3D domain swapping, which can occur once or twice per monomeric unit <ref name="liul">PMID:11224563</ref >.  The 3D domain swapping has no impact on the formation of active sites which is the same in the monomers and all oligomers.<ref name="liul"/>  The oligomers of RNase A also show medical relevance as antitumor drugs as models to understand the possible cause of Alzheimer's.

Not only is the structure of the monomers conserved in the dimers, but the active is also conserved. <ref name="liu98"/>  The active site of both dimers contains His12, Lys41, and His119 residues.  The active sites are a composite of the monomer subunits containing His12 from one monomer and His119 form the other monomer.<ref name="liul"/>  During domain swapping, the active site is not disturbed, so the dimers are able to retain their enzymatic activity.