Whole-cell kinetic constants of PCFT transport with antifolate substrates at pH 5.5
Kt and Vmax were determined with the tritiated substrates [3H]l-AMT, [3H]d-AMT, [3H]PMX, and [3H]MTX in R2/hPCFT4 cells and calculated from Lineweaver Burke plots as described under Materials and Methods. l-MTX results were published previously (Wang et al., 2010). Values are mean values ± S.D. (n = 3).
| Substrate | Kt | Vmax | Vmax/Kt |
|---|---|---|---|
| μM | pmol/mg/2 min | pmol/mg/2 min/μM | |
| d-AMT | 15.0 ± 1.7 | 42.9 ± 13.0 | 2.8 |
| l-AMT | 0.69 ± 0.24 | 68.8 ± 18.5 | 99.7 |
| PMX | 0.26 ± 0.017 | 60.7 ± 8.9 | 233 |
| l-MTX | 0.28 ± 0.035 | 62.5 ± 14.9 | 223 |