LDN-27219 is a reversible and slow-binding inhibitor of tissue transglutaminase (TGases) with IC50 value of 250nM for TGase 2 [1, 2].

LDN-27219 is discovered as a moderately potent inhibitor of TGase. It shows inhibitory activity against hTGase with IC50 value of 0.6μM. LDN-27219 is also a selective inhibitor. It has no effect on Factor XIIIa or caspase 3 at concentration up to 50μM. Besides that, LDN-27219 is found to be mutually exclusive inhibitors with GTP which is an allosteric inhibitor of TGase. It binds at sites other than the GTP site or the active site of the enzyme. The mechanism of LDN-27219 is also not similar with GTP. It has a modest effect on the binding of calcium. Moreover, it is found that LDN-27219 is a competitive inhibitor of the hTGase-catalyzed hydrolysis of Z-Pro-Gln-Ala-Trp [1].

References:
[1] Case A, Stein R L. Kinetic analysis of the interaction of tissue transglutaminase with a nonpeptidic slow-binding inhibitor. Biochemistry, 2007, 46(4): 1106-1115.
[2] Duval E, Case A, Stein R L, et al. Structure–activity relationship study of novel tissue transglutaminase inhibitors. Bioorganic & medicinal chemistry letters, 2005, 15(7): 1885-1889.