Members of this family are predominantly found in chondroitin ABC lyase I, and adopt a jelly-roll fold topology consisting of a two-layered bent beta-sheet sandwich with one short alpha-helix. The convex beta sheet is composed of five antiparallel strands, whilst the concave beta-sheet contains five antiparallel beta-strands with a loop between two consecutive strands folding back onto the concave surface. This domain is required for binding of the protein to long glycosaminoglycan chains.