Article Figures & Data
Figures
- FIGURE 1.
Structures of peptides used in this study. Peptide 1 is HYNIC (Lys)–Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-amide; peptide 2 is HYNIC (Lys)–Gly-His-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-amide; and peptide 3 is HYNIC (Lys)–Gly-Ala-Tyr-Gly-Trp-Met-Asp-Phe-amide. Atoms shown in bold are potentially coordinating.
- FIGURE 2.
Radio-HPLC analysis of peptides 1–3 labeled using tricine and EDDA as coligands.
- FIGURE 3.
(A) Stability of 99mTc-peptides labeled using tricine as a coligand after dilution in PBS or human serum. (B) Stability of 99mTc-peptides labeled using EDDA as coligand after dilution in PBS or human serum.
- FIGURE 4.
Stability of 99mTc-peptides labeled using tricine as coligand after challenge with cysteine.
- FIGURE 5.
Internalization of 99mTc-labeled peptide 1 (P1) and peptide 2 (P2) labeled with tricine and EDDA as coligands. Internalization rates are expressed in relation to that seen with 99mTc-EDDA–peptide 1.
Tables
Peptide Molecular weight Coligand m/z [ES(+)] No. of coligands/assignment Retention time (min) 1 1,279.5 Tricine 1,553.3 [(1 + Tc + tricine – 5H)+H]+ 25.9; 26.0 777.4 [(1 + Tc + tricine – 5H) + 2H]2+ EDDA 1,548.2* [(1 + Tc + EDDA – 5H) + H]+ 25.5 (minor) 1,724.3* [(1 + Tc + 2EDDA – 5H) + H]+ 27.0 2 1,473.5 Tricine 1,747.5 [(2 + Tc + tricine – 5H) + H]+ 26.2; 27.6 874.5 [(2 + Tc + tricine – 5H) + 2H]2+ EDDA 1,744.3 [(2 + Tc + EDDA – 5H) + H]+ 26.9 873.4 [(2 + Tc + EDDA – 5H) + 2H]2+ 1,920.2 [(2 + Tc + 2EDDA – 5H) + H]+ 961.3 [(2 + Tc + 2EDDA – 5H) + 2H]2+ 3 1,207.5 Tricine 1,481.3 [(3 + Tc + tricine – 5H) + H]+ 25.7–27.0 741.5 [(3 + Tc + tricine – 5H) + 2H]2+ 1,660.5 [(3 + Tc + 2tricine – 5H) + H]+ 830.7 [(3 + Tc + 2tricine – 5H) + 2H]2+ All ES data are from positive-mode spectra, unless indicated with an asterisk.
Peptide–coligand combination IC50 (nM) 99m/99Tc-tricine–peptide 1 7.08 ± 0.83 99m/99Tc-tricine–peptide 2 2.98 ± 0.37 99m/99Tc-EDDA–peptide 1 7.48 ± 0.09 99m/99Tc-EDDA–peptide 2 5.70 ± 0.30 - TABLE 3
Biodistribution of 99mTc-Peptides 1 and 2 Radiolabeled Using Tricine as Coligand in CD1 Nude Mice Bearing AR42J Tumor Xenografts at 1 Hour After Injection
Peptide Organ 1 1 blocked 2 2 blocked Liver 3.0 ± 0.7 7.6 ± 2.3 1.5 ± 1.3 2.2 ± 0.3 Kidneys 31.8 ± 5.1 35.9 ± 7.0 12.0 ± 1.6 19.1 ± 7.4 Tumor 0.8 ± 0.4 0.7 ± 0.20 1.7 ± 0.1* 0.6 ± 0.2 Blood 0.9 ± 0.2 1.4 ± 0.6 0.4 ± 0.1 0.6 ± 0.1 Stomach 0.5 ± 0.6 0.9 ± 0.8 1.1 ± 0.3 0.6 ± 0.1 Spleen 0.6 ± 0.1 1.5 ± 0.1 0.5 ± 0.4 0.6 ± 0.1 Intestine 5.9 ± 0.4 10.5 ± 2.2 1.0 ± 0.1 2.8 ± 0.5 Muscle 0.2 ± 0.1 0.4 ± 0.1 0.1 ± 0.0 0.1 ± 0.1 Pancreas 0.4 ± 0.1 0.4 ± 0.3 0.2 ± 0.0 0.2 ± 0.1 ↵* Significant, P = 0.05.
Values are expressed as %ID/g (mean ± SD, n = 3).
- TABLE 4
Biodistribution of 99mTc-Peptides 1 and 2 Radiolabeled Using EDDA as Coligand in CD1 Nude Mice Bearing AR42J Tumor Xenografts at 1 Hour After Injection
Peptide Organ 1 1 blocked 2 2 blocked Liver 1.1 ± 0.3* 0.5 ± 0.2 0.4 ± 0.1 0.3 ± 0.0 Kidneys 10.1 ± 0.7 11.6 ± 1.7 10.3 ± 0.5 12.0 ± 2.4 Tumor 1.5 ± 0.6* 0.8 ± 0.1 2.6 ± 0.2* 0.8 ± 0.2 Blood 0.5 ± 0.1 0.5 ± 0.2 0.4 ± 0.0 0.3 ± 0.0 Stomach 1.9 ± 0.1* 0.4 ± 0.2 0.9 ± 0.5 0.4 ± 0.3 Spleen 0.5 ± 0.2* 0.2 ± 0.1 0.2 ± 0.0 0.1 ± 0.1 Intestine 1.1 ± 0.1 0.8 ± 0.3 0.6 ± 0.3 0.4 ± 0.3 Muscle 0.1 ± 0.0 0.2 ± 0.1 0.1 ± 0.0 0.1 ± 0.0 Pancreas 0.3 ± 0.0 0.2 ± 0.1 0.3 ± 0.0* 0.2 ± 0.0 ↵* Significant, P = 0.05.
Values are expressed as %ID/g (mean ± SD, n = 3).
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