The present invention relates generally to a molecular framework having a cyclic structure. More particularly, the present invention provides cyclic proteins and derivatives thereof in which particular turns and other elements of the molecular structure are held in defined orientations with respect to each other. The cyclic proteins of the present invention provide a molecular framework for the introduction of particular amino acids or heterologous amino acid sequences to facilitate the presentation of biological activities associated with these heterologous amino acid sequences. The molecular framework of the present invention may be naturally cyclic or may be a cyclized derivative of a linear molecular or may be a linear derivative of a cyclized molecule. The present invention contemplates the use of the molecular framework with or without particular amino acids inserted or substituted thereon for the treatment of or prophylaxis of disease conditions in animals, mammals (including humans) and plants.