Fig. 2. The inhibition of human plasma kallikrein by the mixture of stereoisomers 13. ▲ PK15 LLL Ligand 8 (IC₅₀ 2.7 ± 0.10 nM) ■ purified mixture of isomers 13 (IC₅₀ 144 ± 31 nM) crude reaction mixture in the conversion of 12 to 13. (IC₅₀ 238 ± 21 nM).