Fig. 3. Pharmacokinetic analysis of ERC6-complexed Cot-Biotin-Cot peptides.

a The chemical structure of bivalent cotinine-conjugated peptides with crosslinked biotin (Cot-Biotin-Cot peptide). Cot-Biotin-Cot peptides had different amino acid lengths with 6 (GSKGSK), 12 (GGGGSKGGGGSK), or 18 (GGGSGGGSKGGGSGGGSK) amino acid residues between two cotinine molecules. b Pharmacokinetic analysis of ERC6-complexed Cot-Biotin-Cot peptide. Balb/c mice (n = 4) were intravenously injected with 200 µg of ERC6 that was preincubated with 964 pmol of Cot-Biotin-Cot peptide at a 1:1 molar ratio dissolved in 100 µL of sterile PBS. Each group was injected with Cot-Biotin-Cot peptides with 6 (●), 12 (□), or 18 (▲) amino acid residues. Blood samples were collected via the intraorbital vein, and the circulating serum levels of ERC6-complexed Cot-Biotin-Cot peptide were determined via enzyme immunoassays (EIAs). c Circulating serum levels of total ERC6 were also determined via EIAs. The results are shown as the mean ± SD acquired from experiments conducted in triplicate; ^*P < 0.05, ^**P < 0.01 compared with the group, Student’s t test. PBS phosphate-buffered saline