Enzyme | Substrate | Inhibitor Concentration, μM | Cysteine (%) | Inhibitors MPA Nmol Pi/Unit ALP/Min (%) | Cysteine + MPA (%) |
---|---|---|---|---|---|
TNAP (Piase) | pNPP 2000 μM | 0 | 29 ± 1.9 (100) | 32 ± 10 (100) | 28 ± 1.7 (100) |
40 | 28 ± 2.8 (98) | 26 ± 8 (81) | 8 ± 1.6* (29) | ||
400 | 11 ± 1.3* (37) | 17 ± 1.0* (53) | 4 ± 0.8* (14) | ||
4000 | 4 ± 1.0* (12) | 10 ± 2.0* (31) | 3 ± 0.2* (12) | ||
TNAP (PPiase) | Pyrophosphate 2000 μM | 0 | 27 ± 1.9 (100) | 56 ± 3.0 (100) | 55 ± 16.4 (100) |
40 | 30 ± 2.0 (110) | 53 ± 3.0 (93) | 21 ± 4.5* (39) | ||
400 | 18 ± 1.3* (66) | 39 ± 5.0* (70) | 19 ± 4.7* (34) | ||
4000 | 2 ± 1.1* (6) | 27 ± 5.0* (54) | 14 ± 3.7* (25) | ||
TNAP (CPPD crystal dissolution) | CPPD 345 μM (100 μg) | 0 | 0.46 ± 0.07 (100) | 0.26 ± 0.11 (100) | 0.26 ± 0.02 (100) |
40 | 0.49 ± 0.09 (107) | 0.25 ± 0.01 (96) | 0.23 ± 0.01 (88) | ||
400 | 0.43 ± 0.04 (93) | 0.24 ± 0.01 (92) | 0.10 ± 0.007* (38) | ||
4000 | 0.15 ± 0.02* (33) | 0.07 ± 0.01* (27) | 0.00 ± 0.05* (0) |
↵* Calculated value with inhibitor present is statistically significantly different (p < 0.05) from the value with no inhibitor. TNAP: tissue-nonspecific alkaline phosphatase; CPPD: calcium pyrophosphate dihydrate; pNPP: p-nitrophenyl phosphate; ALP: alkaline phosphatase.