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Table 1 Physicochemical properties of free and DOTA-coupled dimeric peptide NPY analogs

From: Novel dimeric DOTA-coupled peptidic Y1-receptor antagonists for targeting of neuropeptide Y receptor-expressing cancers

Analog number Amino acid residues N-term Purity (%) MSc
  Xa 29 Xa 29' Xb Xc DOTA HPLC a CZE b calc obs
1 Asn Asn Tyr Leu No 98 98 2,389.2 2,390.3
2 Asn Asn Tyr Leu Yes 97 96 3,161.6 3,162.6
3 Asn Asn Trp Nle No 94 90 2,435.2 2,436.5
4 Asn Asn Trp Nle Yes 95 92 3,207.6 3,208.8
5 Dpr Dpr Trp Nle No 99 96 2,379.3 2,380.1
6 Dpr(DOTA) Dpr(DOTA) Trp Nle No 94 93 3,151.6 3,152.4
7 Dpr Asn Trp Nle No 99 99 2,407.3 2,408.5
8 Dpr(DOTA) Asn Trp Nle No 98 97 2,793.5 2,794.9
9 Lys Lys Trp Nle No 88 84 2,463.4 2,464.5
10 Lys(DOTA) Lys(DOTA) Trp Nle No 92 96 3,236.3 3,236.8
11 Lys (DOTA) Asn Trp Nle No 83d 83 2,834.5 2,835.3
  1. aPercentage purity determined by HPLC using buffer system: A = TEAP (pH 2.5) and B = 60% CH3CN/40% A with a gradient slope of 1% B/min, at flow rate of 0.2 mL/min on a Vydac C18 column (0.21 cm × 5 cm, 5-μm particle size, 300-Å pore size). Detection at 214 nm. bPercentage purity determined by capillary zone electrophoresis (CZE) using a Beckman P/ACE System 2050; field strength of 15 kV at 30°C. Buffer, 100 mM sodium phosphate (85:15, H2O:CH3CN), pH 2.50, on a Agilent μSil bare fused-silica capillary (75 μm i.d. × 40 cm length). Detection at 214 nm. cMALDI mass spectral analysis (m/z). The observed [M + H]+ of the monoisotopic mass (obs) compared with the calculated m/z of the monoisotope (calc). dThe detectable contaminant, produced during the dimerization process of this heterodimer, was identified as analog 3.