KNOTTED STRUCTURES IN CHEMISTRY, BIOCHEMISTRY, AND MOLECULAR-BIOLOGY

The term ''knot'' in the mathematical sense, as a closed curve in 3-sp ace that does not intersect itself but that cannot be embedded in the plane without intersections, has been used to describe a wide variety of molecular structures - except in the protein literature, where it h as been used to describe structural motifs that are neither closed kno ts in the above sense nor even knots in the everyday sense. We argue i n this paper that description of these motifs as ''knots'' constitutes ''improper'' use of scientific terminology, and we propose a definiti on of ''molecular knot''.