Table 1. Amino Acid Composition of the CDPs Used in This Studya.
| CDP | pos. 1 | pos. 3 | pos. 4 | pos. 5 | pos. 6 | pos. 8 | pos. 9 | pos. 10 | PAMPA log Pe |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Leu | Leu | d-Ala | M-Phe | Leu | Leu | d-Ala | M-Phe | –5.9 |
| 2 | Leu | Leu | d-Ala | M-Ala | Leu | Leu | d-Ala | M-Ala | –4.0 |
| 3 | Leu | Leu | d-Pro | M-Phe | Leu | Leu | d-Pro | M-Phe | –5.3 |
| 4 | Leu | Leu | d-Pro | M-Phe | Leu | Leu | d-Pro | M-Ala | –4.2 |
| 5 | Leu | Leu | d-Pro | M-Ala | Leu | Leu | d-Pro | M-Ala | –4.6 |
| 6 | Ala | Leu | d-Pro | M-Phe | Ala | Leu | d-Pro | M-Phe | –4.1 |
| 7 | Ala | Ala | d-Pro | M-Phe | Leu | Leu | d-Pro | M-Phe | –4.4 |
| 8 | Ala | Ala | d-Pro | M-Phe | Ala | Ala | d-Pro | M-Phe | –6.4 |
a
d-Amino acids are marked with the letter d, methylated amino acids are marked with the letter M. The amino acids at position 2 and 7 (M-Ala) were kept constant. The parallel artificial membrane permeation assay (PAMPA) coefficients were taken from ref (69). CDP 1 and 8 with log Pe < −5.5 can be considered non-permeable.