Depicting topology and handedness in jellyroll structures

The jellyroll structure is a special case of the Greek key topology and, to date, has only been observed in complete form in one of its four possible arrangements. Like other elements of super‐secondary structure involving the β‐strand (eg. the βαβ unit) the known structure forms a right‐handed superhelix. The possibility of losing such tertiary information and other problems associated with representing these structures by two‐dimensional topology diagrams are discussed. A series of rules are presented which allow this three‐dimensional information to be represented in two‐dimensional topology diagrams from which the handedness of a jellyroll structure can be determined.