Substrates often used for characterizing newly isolated PPIases, subtilisins or other enzymes. Bachem offers Suc-Ala-Ala-Pro-Xaa (Suc-AAPX) substrates containing Ala, Leu, Met, Nle, and Nva (the pancreatic elastase substrates L-1775, L-1390, L-1395, and L-1780), Arg, Asp, Glu, Ile, Lys, Orn, Phe (the PPIase substrates I-1465, L-1400, and M-2305), and Val (the neutrophil elastase substrates I-1490 and L-1770) as Xaa.

Suc-AAPK-pNA, a substrate for wild-type and K188D/D189K trypsins (Km = 105 mM respectively 651 mM).