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. Author manuscript; available in PMC: 2014 Feb 27.
Published in final edited form as: J Am Chem Soc. 2013 Feb 8;135(8):3173–3185. doi: 10.1021/ja311408y

Figure 3. X-ray structure of ester insulin (1.6 Å), obtained from racemic crystallization of D-DKP ester insulin and L-DKP ester insulin.

Figure 3

(a) Racemic crystal packing in centrosymmetric P1‒ unit cell, showing the L-DKP ester insulin molecule (green) and the D-DKP ester insulin molecule (gold). The ester linkage is shown in sticks (O, red). (b) Cartoon representation of the A chain (cyan) and B-chain (green) of L-DKP ester insulin. The three disulfide bonds of the folded protein and the ester linkage are shown as sticks (O, red; S, gold). (c) SigmaA-weighted 2Fo-Fc electron density map, contoured at 1.5σ, showing the ester linkage between GluA4-ThrB30 (C, green; O, red; N, blue). (d) Superposition of X-ray crystal structures the T-form of KP insulin (PDB ID: 1LPH) (magenta) and DKP ester insulin (green). The three disulfide bonds and the ester linkage are shown as sticks (O, red; N, blue S, gold).