A) SDS-PAGE gel of the reactions of CdSrtA3M where the X position varied. Reactions (200 μM enzyme, 200 μM NSpaA, 5 mM DTT, and 1 mM Peptide) were measured after 24 hours. The majority of the more active sorting signals were non-polar while the polar residues tended to decrease the activity relative to the original sorting signal (LPLTG). B) SDS-PAGE gel of the reactions of CdSrtAΔ where the X position varied in the LPLTG Peptide. Reactions (200 μM enzyme, 200 μM NSpaA, 5 mM DTT, and 1 mM Peptide) were measured after 24 hours. C) Images were analyzed with Image J which estimated the amount of product produced for each peptide in the library.