Inhibitor   Inhibition mode Free-GHTHase PEG-GHTHase   Propargylglycine IC50 (mM)   3.3 3.8   Ki (µM) Competitive 726 1091 Noncompetitive 3266 3807 Uncompetitive 2540 2715 Hydroxylamine IC50 (mM)   2.2 2.7 Ki (µM) Competitive 489 767 Noncompetitive 2199 2675 Uncompetitive 1710 1908 Iodoacetate IC50 (mM)   1.4 1.6 Ki (µM) Competitive 303 453 Noncompetitive 1362 1580 Uncompetitive 1059 1126

Table 2: Kinetic parameters of inhibition of free and PEG-GHTHase for specific suicide inhibitor.