Protein topology

Two main topology frameworks have been developed and applied to protein molecules. Knot Theory Knot theory which categorises chain entanglements. The usage of knot theory is limited to a small percentage of proteins as most of them are unknot. Circuit topology Circuit topology categorises intra-chain contacts based on their arrangements. Circuit topology is a determinant of protein folding kinetics and stability. ==Other uses==

In biology literature, the term topology is also used to refer to mutual orientation of regular secondary structures, such as alpha-helices and beta strands in protein structure For example, two adjacent interacting alpha-helices or beta-strands can go in the same or in opposite directions. Topology diagrams of different proteins with known three-dimensional structure are provided by PDBsum ([http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1qjp&template=protein.html&r=wiring&l=1&chain=A an example). ==See also==