Figure 4.

Theoretical binding mode of Saq B₁ to PI3Kα protein. (A) AutoDockTools software was used to obtain the optimal docking model of Saq B₁ to the PI3Kα protein, and the image obtained was a 3D panorama of the optimal binding mode. (The chemical structure of Saq B₁ is represented by a red rod-shaped structure, the blue band represents the spatial structure of the PI3Kα protein, and the purple rod-shaped structure represents the amino acid residue bound to Saq B₁). The lowest binding energy configuration is −8.34 kcal/mol. (B) The simplified two-dimensional interaction model is presented, in which some carbonyl and hydroxyl groups of Saq B₁ are hydrogen-bonded to amino acid residues, while the D-olivose and benzene ring are bonded to amino acid residues Pro447, Trp446, and Pro449 in the form of alkyl.