TABLE 1.
Km and Vmax values of ACER2 for different substrates
Δypc1Δydc1ACER2 microsomes (40 μg of proteins per reaction) were measured for ceramidase activity at pH 9.0 using different concentrations of various ceramides as substrates in the presence of Triton X-100 (0.15%, v/v) and CaCl2 (1 mm). The apparent Km and Vmax values were computed according to nonlinear regression by GraphPad Prism software. Data represent mean ± S.D. of three independent experiments.
| Substrates | Km | Vmax | Vmax/Km |
|---|---|---|---|
| μm/mol % | pmol/min/mg | μm | |
| C6:0-Cer | 224.16 ± 37.51/8.45 ± 1.41 | 5.04 ± 0.72 | 0.02 ± 0.00 |
| C12:0-Cer | 133.83 ± 17.88/5.05 ± 0.67 | 10.67 ± 1.54 | 0.08 ± 0.02 |
| C14:0-Cer | 114.61 ± 13.28/4.32 ± 0.50 | 11.37 ± 1.41 | 0.10 ± 0.03 |
| C16:0-Cer | 98.52 ± 11.79/3.71 ± 0.44 | 23.70 ± 3.18 | 0.24 ± 0.03 |
| C18:0-Cer | 94.81 ± 10.06/3.57 ± 0.38 | 26.11 ± 3.47 | 0.28 ± 0.05 |
| C18:1-Cer | 77.31 ± 8.43/2.91 ± 0.32 | 35.42 ± 5.10 | 0.46 ± 0.07 |
| C20:0-Cer | 91.47 ± 9.79/3.45 ± 0.37 | 28.94 ± 3.61 | 0.32 ± 0.04 |
| C20:1-Cer | 72.11 ± 8.52/2.71 ± 0.32 | 38.16 ± 4.74 | 0.53 ± 0.08 |
| C24:0-Cer | 143.2 ± 18.16/5.39 ± 0.68 | 6.74 ± 0.87 | 0.05 ± 0.00 |
| C24:1-Cer | 81.40 ± 10.21/3.06 ± 0.38 | 27.07 ± 3.78 | 0.33 ± 0.06 |