Structural details of the insulin molecule.

<p><b>(A)</b> The structure of the insulin (PDB ID: 2G4M). A-Chain (orange); B-chain N-terminal (residues F1–G8) (red), B-chain α-helix (residues S9–C19) (black), B-chain C-terminal (residues G20–T30) (blue). The colored spheres represent the C<sub>α</sub> atoms of the first and last residues of the A and B-chains. <b>(B)</b> The new ribbon representation shows the hydrophobic core of insulin, comprising the residues F24, L15, Y26, L11, V12, G8 (side chains shown in cyan), I2<sub>A</sub> and V3<sub>A</sub> (side chains shown in green). The hydroxyl group of Y26 and the oxygen atom of G8 are shown in red, and the disulfide bridges in yellow. <b>(C)</b> The hydrogen bonds between the residues neighboring Y24 and the A chain residues, G23(O)–N2<sub>A</sub>(N) and F25(N)–Y19<sub>A</sub>(O), are illustrated in blue dashed lines. Oxygen and nitrogen atoms are represented in red and blue, respectively.</p>