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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.