Structure of Monomeric Porcine DesB1-B2 Despentapeptide (B26-B30) Insulin at 1.65 Å Resolution

Insulin has a concentration of 10^-8-10^-11 M in the blood which ensures that it circulates and exerts its physiological functions in vivo as a monomer. The crystal structure of monomeric porcine desB1-B2 despentapeptide (B26-B30) insulin (DesB1-2 DPI) with M_r = 4934 Da has been determined at 1.65 Å resolution using the molecular replacement method. A structural comparison between DesB1-2 DPI and 2Zn insulin reveals that the conformation of DesB1-2 DPI is more similar to molecule I than molecule II of 2Zn insulin. The remarkable conformational difference between B25-Phe in DesB1-2 DPI and B25-Phe in despentapeptide (B26-B30) insulin (DPI) indicates that the residue B25-Phe possesses great flexibility and mobility.