An enzyme with a deep trefoil knot for the active-site architecture.
Nureki, O., Shirouzu, M., Hashimoto, K., Ishitani, R., Terada, T., Tamakoshi, M., Oshima, T., Chijimatsu, M., Takio, K., Vassylyev, D.G., Shibata, T., Inoue, Y., Kuramitsu, S., Yokoyama, S.(2002) Acta Crystallogr D Biol Crystallogr 58: 1129-1137
- PubMed: 12077432 
- DOI: 10.1107/s0907444902006601
- Primary Citation of Related Structures:  
1IPA - PubMed Abstract: 
Knots in polypeptide chains have been found in very few proteins. Only two proteins are considered to have a shallow 'trefoil' knot, which tucks a few residues at one end of the chain through a loop exposed on the protein surface. Recently, another protein was found by a mathematical algorithm to have a deep 'figure-of-eight' knot which had not been visually identified ...