Disease Markers

Research Article

Altered Peptidase Activities in Thyroid Neoplasia and Hyperplasia

Table 1

Substrates and the reaction conditions for each enzymatic assay.
 Substrates(mM)pHaDTT (mM)EDTA (mM)CaCl2  (mM)NaCl (mM)MnCl2  (mM)
PEP (EC 3.4.21.26)Z-Gly-Pro-β-NA0,1257,42————
PGI (EC 3.4.19.3)pGlu-β-NA0,1257,422———
APBb  (EC 3.4.11.6)Arg-β-NA0,1256,5———150—
APN/CD13b  (EC 3.4.11.2)Ala-β-NA0,1257,41,2————
AlaAP (EC 3.4.11.14)Ala-β-NA0,1257,41,2————
APA (EC 3.4.11.7)H-Glu-β-NA0,1257,40,65—0,5——
AspAP (EC 3.4.11.21)Asp-β-NA0,1257,4————1
DPPIV/CD26 (EC 3.4.14.5)H-Gly-Pro-β-NA0,28,3—————
CAP (EC 3.4.11.3)L-Cys-di-β-NA0,1255,9—————
NEPc  (EC 3.4.24.11)N-Dansyl-D-Ala-Gly-pNO2-Phe-Gly0,1257,4—————
Reaction buffers: Phosphate buffer (50 mM) was used for PEP, PGI, APB, APN/CD13, and AlaAP. Tris-HCl (50 mM) was used for APA, AspAP, DPPIV/CD26, CAP, and NEP. b40 μM of the AlaAP inhibitor puromycin was added; c4.6 nM of the angiotensin-converting enzyme inhibitor captopril was added.