Crystal structure of form B monoclinic crystal of insulin

The form B monoclinic insulin crystal was crystallized in space group P2p, with cell parameters a = 4.924 nm, b = 6.094 nm, c= 4.818 nm, β= 95.8°. There is one hexamer insulin molecule per asymmetric unit. The structure determination was carried out by molecular replacement techniques and refined with 0.25 nm data to a crystallographic R factor of 20.6% . The root mean-square deviation from ideal bond lengths and ideal angles is 0-002 0 nm and 3.858° respectively. Each hexamer has 3-fold noncrystallographic symmetry and all six insulin molecules have helical conformation from B1 to B20. Six phenol molecules were found bonding specifically to each molecule, evidently stabilizing the helical conformation.