Fig. 8: Crystal structure of α-chymotrypsin in complex with a ‘two rings’ macrocyclic peptide.
a Molecular surface representation of bovine α-chymotrypsin (PT5; grey) in complex with the ‘two rings’ macrocyclic peptide MP5.4.3 (light blue). A large surface (784 Å2) of PT5 is covered by MP5.4.3. Detailed view of the first (b, top) and second (c, bottom) ring of MP5.4.3 (light blue) bound to PT5 (white) shown in two orientations (180° rotation). The side-chains of the residues are shown as sticks. Only the residues involved in key inter-molecular interactions (black dashed lines) are shown. Amino acid side-chains are shown as sticks and coloured by atom type (carbon: light blue, oxygen: firebrick, nitrogen: deep blue, sulfur: yellow-orange). d Zoomed-in view of the protein complex structure showing the residues of PT5 (white), known to define the primary substrate-binding pocket called S1 binding pocket (S189–S195, S214–C220 and P225–Y228)60,95, surrounding and forming multiple interactions with the side-chain of Trp4 (W4) of MP5.4.3. e Left, columns graph (grey) reporting the total number of polar (both direct and H2O mediated) and non-polar inter-molecular interactions established by PT5 with the ‘two rings’ macrocyclic peptide MP5.4.3. Right, columns graph (grey) reporting the total number of inter-molecular interactions mediated by either side-chain atoms (s) and/or main-chain atoms (m) of MP5.4.3 (top) with either side-chain atoms (s) and/or main-chain atoms (m) of PT5 (bottom). Data for e are provided as Source data.
