In general proteins are open chains, but some of them have some kind of extra closure (e.g. cysteine bridge, isopeptide bond, metal ion bridge) which alters their topology. Because of these closures we can find loops, lassos, handcuffs, theta-curves or more complicated structures inside the protein. They are especially interesting if because of tangling they cannot be represented as a planar graph. It has been shown that such complex topologies like knots and lassos can perform important role in protein function.

During my seminar I want to show you results about complex lasso and handcuff topologies which I collected during my PhD and earlier. Moreover I want to introduce you to methods which I use, show their weaknesses and how I want to improve them.