Single crystals of destripeptide (B28-B30) insulin (DTRI) in three forms we
re obtained by hanging-drop vapor diffusion method. Form I belongs to P2(1)
space group with cell parameters a=4.77 nm, b=6.19 nm, c=6.12 nm, beta=110
.3 degrees. Form 2 belongs to P4(1)22 or P4(3)22 space group with cell para
meters a= 6.45 nm, c=2.07 nm. Form 3 belongs to P2(1)2(1)2(1) space group w
ith cell parameters a=4.98 nm, b=5.16 nm, c=10.06 nm. The structure of form
1 crystal was determined by molecular replacement method and refined at 0.
23 nm resolution. The R-factor of the final model is 18.8% with r.m.s. devi
ations of 0.001 5 nm and 3.3 degrees for the bond lengths and the bond angl
es, respectively. Studies on the crystal structure show that the removal of
B28 Pro has brought DTRI structural changes which made it dissociate more
easily than native insulin although DTRI can still form a hexamer.