Table 1.

Substrate selectivity of human FAAH expressed in COS-7 cells and comparison to rat FAAH

Substrate	Human FAAH rate of hydrolysis, nmol·min−1·mg−1	Human FAAH % hydrolysis rate	Rat FAAH % hydrolysis rate
Anandamide, 100 μM	30.7  ± 1.5	100	100
Oleamide, 100 μM	21.5  ± 0.9	70	73
Myristic amide, 100 μM	19.8  + 1.4	65	24
Palmitic amide, 100 μM	10.2  ± 0.4	33	10
Oleamide, 20 μM	5.5  ± 0.2	100	100
Stearic amide, 20μM	0.32 + 0.01	5.8	5.8

FAAH activity measured in transfected COS-7 cells with various ¹⁴C-fatty acid amides as substrates. Anandamide and oleamide hydrolysis rates were considered to be 100% of FAAH activity where indicated, to which other fatty acid amide hydrolysis rates were compared. Previously measured relative rates of fatty acid amide hydrolysis for the rat FAAH (23) are listed in the final column for comparison.