886992-99-0

Ki: 23 nM (FAP)

FAP has been implicated in cancer; however, its specific role remains elusive because inhibitors that distinguish FAP from other prolyl peptidases like dipeptidyl peptidase-4 (DPP-4) have not been developed. Ac-Gly-BoroPro selectively inhibits FAP relative to other prolyl peptidases. FAP reacts readily with submicromolar concentrations of Ac-Gly-BoroPro, reaching steady state inhibition levels rapidly (K _i =23±3 nM). In contrast, DPP-4 requires higher Ac-Gly-BoroPro concentrations for inhibition and a longer time to reach steady state inhibition levels (K _i =377±18 nM). Ac-Gly-BoroPro inhibits other prolyl peptidases (DPP-7, DPP-8, DPP-9, prolyl oligopeptidase, and acylpeptide hydrolase) with K _i values ranging from 9- to 5400-fold higher than that for FAP inhibition. The N-acyl-linkage in Ac-Gly-BoroPro blocks the N terminus of the inhibitor, making it less nucleophilic and therefore unlikely to cyclize.