Preparation of indium-115-labeled diethylenetriaminetetraacetic acid monoacetamide peptides purified by 8-hydroxyquinoline

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In this communication we describe a novel procedure for the preparation and purification of diethylenetriaminepentaacetic (DTPA)-acylated and 115In3+ -labeled oligopeptides using 8-hydroxyquinoline for the removal and quantification of nonbound indium ions. First the N(α) or N(α), N(ε)-DTPA oligopeptides containing C-terminal KDEL signal motif were produced by solid-phase synthesis. For this the free carboxyl group of DTPA dianhydride was activated in situ for a short period of time yielding a major product. Reversed-phase HPLC-purified DTPA oligopeptides were labeled with 115In3+ in aqueous buffer solution at pH 3.8. For the removal as well as for the detection of uncoordinated 115In3+ ions we have utilized the 115In3+ complex-forming ability of 8-hydroxyquinoline in chloroform. Following an optimized extraction procedure the free indium ion content was measured by spectrophotometry in the organic phase. Data obtained by this method and verified by total-reflection X-ray fluorescence spectroscopy and thin-layer chromatography demonstrated that free 115In3+ could be efficiently removed and sensitively detected in the presence of DTPA oligopeptide chelator. No release of 115n3+ from its DTPA complex was observed. This method could be useful for the preparation of indium complexes of peptides and perhaps proteins containing a DTPA moiety and nonradioactive isotope ligand. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)17-24
Number of pages8
JournalAnalytical Biochemistry
Issue number1
Publication statusPublished - Dec 1 2000

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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