Fig. 5. Distance analysis and top view of the unnatural side chain at position 15 of BPTI depicted in orange within the S1 binding pocket of β-trypsin drawn in blue. Values indicate the distance in Å between the individual hydrogen or fluorine atoms of the terminal γC of the side chain and the ten nearest enzyme atoms (clockwise, Gln192NE, Gln192CD, Gln192CA, Gln192N, Cys191C, Cys191CA, Cys191N, Ser190C, Ser190CA, and Ser190N), as well as the five nearest BPTI atoms (from top to bottom, Xaa15CA, Xaa15N, Cys14C, Cys14CA, and Pro13O): (a) Abu structure with side chain and structural waters A–D in light blue and the three γC hydrogen substituents HG1 (ABAHG1), HG2 (ABAHG2), and HG3 (ABAHG3) in light-gray; (b) DfeGly structure with side chain and structural waters A–D in magenta, the two γC fluorine substituents FG1 (OBFFG1) and FG2 (OBFFG2) in green, and the single γC hydrogen substituent HG (OBFHG) in gray; (c) TfeGly structure with side chain and structural waters A–D in black and the three γC fluorine substituents FAD (3EGFAD), FAE (3EGFAE), and FAC (3EGFAC) in green. Nitrogen atoms are shown in dark blue and oxygen atoms in red.
