Inhibition constants (Ki) of different derivatives for the inhibition of l-[3H]proline and [3H]glycine uptake in Caco-2 cells Uptake of l-[3H]proline (10 nM) and [3H]glycine (30 nM) was measured at pH 6.0 for 10 min in the presence of unlabeled amino acids and derivatives. Inhibition curves for calculation of Ki values are shown in Fig. 3. Parameters are shown ± S.E. (n = 4).
Inhibitor | Ki Values | ||
|---|---|---|---|
| l-[3H]Proline Uptake | [3H]Glycine Uptake | ||
| mM | |||
| l-Proline | 1.6 ± 0.04 | 2.2 ± 0.2 | |
| d-Proline | 1.2 ± 0.3 | 1.9 ± 0.1 | |
| cis-4-Hydroxy-l-proline | 30 ± 4 | ∼ 45 ± 13 | |
| cis-4-Hydroxy-d-proline | 3.5 ± 0.1 | 3.2 ± 0.2 | |
| trans-4-Hydroxy-l-proline | 9.0 ± 0.9 | 5.3 ± 0.6 | |
| l-Azetidine-2-carboxylic acid | 1.8 ± 0.1 | 1.9 ± 0.4 | |
| 3-Amino-1-propanesulfonic acid | 7.1 ± 0.6 | 10.5 ± 0.5 | |
| Glycine | 5.1 ± 0.9 | 9.2 ± 1.0 | |
| N-Methyl-l-alanine | 2.2 ± 0.1 | 2.0 ± 0.1 | |