STRUCTURAL-ANALYSIS OF DESHEPTAPEPTIDE (B24-B30) INSULIN BY MOLECULARREPLACEMENT

Desheptapeptide (B24-B30) insulin (DHPI), a virtually inactive insulin analog, has been crystallized in space group P2(1)2(1)2(1) with two D HPI molecules in an asymmetric unit. The orientations and positions of the molecules were determined by molecular replacement, and a structu ral model was built at 0.3 nm resolution. The current model shows that the two DHPI monomers are related by a non-crystallographic 2-fold ax is, nearly parallel to the crystallographic c axis. This structural fe ature complicated the determination of the orientation of the local 2- fold axis, which was later confirmed by analysing the diffraction data of DHPI crystals.