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Most Complicated Knot Image 2
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Most Complicated Knot (Image 2)

June 22, 2010
Most Complicated Knot (Image 2) This simplified diagram of human ubiquitin hydrolase UCH-L3 shows the knot in the protein. The protein crosses itself five times. MIT researchers recently found that ubiquitin hydrolase UCH-L3 has the most complicated knot ever observed in a protein. Knots are rare in proteins -- less than 1 percent of all proteins have any knots, and most are fairly simple. The researchers analyzed 32,853 proteins, using a computational technique never before applied to proteins at this scale. Of those that had knots, all were enzymes. Most had a simple three-crossing, or trefoil knot, a few had four crossings, and the most complicated, a five-crossing knot, was initially found in only one protein -- ubiquitin hydrolase. That complex knot may hold some protective value for UCH-L3, whose function is to rescue other proteins from being destroyed -- a dangerous job. To learn more about this research, see the MIT Sept. 20, 2006, News Release, "Knotty Problem Puzzles Protein Researchers." This research was supported by National Science Foundation grant DMR 04-26677. [From Virnau P. A., Mirny L., Kardar M. (2006) Intricate Knots in Proteins: Function and Evolution. PLoS Comput Biol 2(9): e122.] [One of three related images. See Next Image.] (Date of Image: Sept. 2006)