TABLE 2.
Michaelis-Menten parameters of the cleavage by trypsin of FAM-APP(684–726) at the α-cleavage site
| System | KM [μM] | KM′ [μM]* | Vmax [nmol/min] per mg enzyme | kcat [s−1] | Vmax/KM [mL/min] per mg enzyme | Vmax/KM′ [mL/min] per mg enzyme |
|---|---|---|---|---|---|---|
| Tris buffer containing 1% acetonitrile | 3.51/4.85 | — | 46.7/49.7 | 0.018/0.019 | 13.3/10.2 | 13.3/10.2 (Vmax/KM) |
| DMPC liposomes | >60 | >30 | >1000 | >0.39 | 6.1 ± 3.4 | 12.2 ± 6.8 |
| PhC liposomes | >60 | >30 | >1000 | >0.39 | 7.7 ± 0.8 | 15.5 ± 1.7 |
| DSPC liposomes | 36.5/19.9 | 18.2/10.0 | 198/189 | 0.077/0.074 | 5.4/9.5 | 10.8/18.9 |
| Sph liposomes | 63.9 ± 15.9 | 31.9 ± 8.0 | 918 ± 355 | 0.36 ± 0.14 | 14.3 ± 3.1 | 28.5 ± 6.1 |
Mean values from three independent experiments with SD are shown, except for soluble APP and DSPC with values from two independent experiments.
*
KM′, KM corrected for the estimated fraction of peptide oriented with the cleavage site outside the liposomes (KM′= KM/2).