Complex sentence: The structures of chorismate mutases vary in different organisms, but the majority belong to the AroQ family and are characterized by an intertwined homodimer of 3-helical subunits.
Split into simpler sentences: The structures of chorismate mutase vary in different organisms, but the majority belongs to the AroQ family. That is, they are characterized by an intertwined homodimer of 3-helical subunits.