Based on the extensive structural comparisons among the determined str
uctures of the different species and crystal forms of insulin and its
derivatives in our laboratory, it was suggested that the binding inter
action with the receptor molecule should take place mainly on an amphi
pathic surface of the insulin molecule. In the middle of this amphipat
his surface, there was a hydrophobic surface with an area of about 150
Angstrom(2), while the polar and charged groups distributing around t
he hydrophobic surface constructed a hydrophilic zone. The hydrophobic
surface was usually covered by the extended B-chain C-terminal peptid
es with great mobility. The angle between the proposed binding interac
tion surface and the surface of dimerization was about 20 degrees. The
results from studies on structures of Al-(L-Trp) insulin and Al-(D-Tr
p) insulin confirmed the interaction mechanism model we proposed.