... sub5910 strates of H+ ⁄ peptide cotransporters, such as Gly-Sar, Ala-Ala, Lys-Lys, Ala-Asp, d-Phe-Ala, Ala-Ala-Ala, d-aminolevulinic acid, cefadroxil and Ala-4-nitroanilide (all 100 lm, Table 1) ... UK) Dexamethasone, apotransferrin, Gly-Gln, AlaAla, Ala-Ala-Ala, Lys-Lys, d-aminolevulinic acid, cefadroxil, Gly, Pro-Ala, 8-aminooctanoic acid and Gly-Sar were from Sigma-Aldrich (Deisenhofen, ... reversible, suggesting a competitive mode of action Uptake of Bip-[3H]Pro by SKPT cells After characterization of Bip-Pro as a very high-affinity and enzymatically stable substrate of PEPT1 and PEPT2, the...