Table 1.

Binding constants for the follower peptide and mutants

Ligand	IC50 (μM)	Ki (μM)
Presegetalin A1 [20–32]	1.97 ± 0.34	0.40 ± 0.007
Presegetalin A1 [14–32]*	3.03 ± 0.61	1.10 ± 0.22
Presegetalin A1 [27–32]	47.4 ± 1.0	31.0 ± 0.65
Presegetalin A1 [27–32] N27A	197 ± 8	131 ± 5
Presegetalin A1 [27–32] amide	>1,000	>650

^*Presegetalin A1 [14–32] binding experiments were completed with PCY1 H695A to prevent turnover.