Table 4.
Kinetic constants for substrates used in this studya
| Organism | Km app (μM) | Vmax app (nmol/min/mg) |
|---|---|---|
| p-Nitrophenyl acetateb | ||
| Salmon | 154 ± 13 | 363,000 ± 14,000 |
| Medaka | 95 ± 12 | 198,000 ± 19,000 |
| Splittail | 578 ± 30 | 129,600 ± 4300 |
| Rainbow troutc | 27.9 ± 12.7 | 672,000 ± 92,100 |
| Porcine esterase | 248 ± 17 | 2,103,000 ± 67,000 |
| Acetated | ||
| Salmon | 30.4 ± 6.1 | 270 ± 23 |
| Medaka | 30.3 ± 8.2 | 29.2 ± 3.4 |
| Splittail | 5.8 ± 1.1 | 7.0 ± 0.4 |
| Porcine esterase | 29.2 ± 2.3 | 2800 ± 100 |
| Butyratee | ||
| Salmon | 7.8 ± 1.0 | 77.4 ± 2.8 |
| Medaka | 16.8 ± 2.0 | 8.7 ± 0.3 |
| Splittail | 8.2 ± 1.7 | 16.4 ± 1.0 |
| Porcine esterase | 12.2 ± 2.5 | 16,100 ± 1100 |
a
Salmon data are from liver homogenates. Medaka and splittail data are from whole body homogenates, and porcine esterase data are from a commercial partly purified preparation. Data are the average of 3 independent determinations ± the standard deviation.
b
Kinetic constants were determined for the substrate p-nitrophenyl acetate (PNPA).
c
Data are from Barron et al. (1999) using rainbow trout liver.
d
Kinetic constants were determined for the substrate α-cyano(6-methoxy-2-naphthyl)methyl acetate (acetate).
e
Kinetic constants were determined for the substrate α-cyano(6-methoxy-2-naphthyl)methyl butyrate (butyrate).