Pierced Lasso Bundles Are a New Class of Knot-like Motifs

Pierced Lasso Bundles Are a New Class of Knot-like Motifs

A four-helix bundle is a well-characterized motif often used as a target for designed pharmaceutical therapeutics and nutritional supplements. Recently, we discovered a new structural complexity within this motif created by a disulphide bridge in the long-chain helical bundle cytokine leptin. When oxidized, leptin contains a disulphide bridge creating a covalent-loop through which part of the p...

Complex lasso: new entangled motifs in proteins

We identify new entangled motifs in proteins that we call complex lassos. Lassos arise in proteins with disulfide bridges (or in proteins with amide linkages), when termini of a protein backbone pierce through an auxiliary surface of minimal area, spanned on a covalent loop. We find that as much as 18% of all proteins with disulfide bridges in a non-redundant subset of PDB form complex lassos, ...

A New Class of Banach Sequence Spaces

Ileoileal Knot as a Content of Obstructed Hernia: What Are the Odds?

An obstructed inguinal hernia is a common surgical emergency, which presents with a variety of contents like the small intestine, omentum, and colon. Intestinal knotting is a rare entity encountered in surgical practice; it occurs when one coil of intestine wraps around the other and eventually leads to complications such as intestinal obstruction, ischemia, and gangrene. Both conditions are co...

Fintushel–Stern knot surgery in torus bundles

Suppose that X is a torus bundle over a closed surface with homologically essential fibers. LetXK be the manifold obtained by Fintushel–Stern knot surgery on a fiber using a knot K ⊂ S. We prove that XK has a symplectic structure if and only if K is a fibered knot. The proof uses Seiberg–Witten theory and a result of Friedl–Vidussi on twisted Alexander polynomials.