Synthesis and characterization of two (111)In-labeled DTPA-peptide conjugates

Bioconjug Chem. 2001 Jul-Aug;12(4):630-4. doi: 10.1021/bc010013h.

Abstract

This report describes the synthesis and characterization of two (111)In-labeled DTPA-peptide conjugates (DTPA-MA and DTPA-BA). It is surprising to find that (111)In(DTPA-MA) and (111)In(DTPA-BA) are more hydrophilic than their corresponding (90)Y analogues, suggesting a different coordination sphere in (111)In and(90)Y complexes of the same DTPA-peptide conjugate. By a reversed phase HPLC method, both (111)In(DTPA-MA) and (111)In(DTPA-BA) showed only one radiometric peak in their respective HPLC chromatogram due to a rapid interconversion of different isomers (particularly cis and trans isomers for (111)In(DTPA-MA); cis-cis, cis-trans, trans-cis, and trans-trans isomers for (111)In(DTPA-BA)). The interconversion of different isomers involves the "wagging" of the diethylenetriamine backbone, "shuffling" of the NO or NO(2) donor sets, and a rapid inversion at the terminal amine-nitrogen atoms.

MeSH terms

  • Chromatography, High Pressure Liquid
  • Indium Radioisotopes / chemistry*
  • Isomerism
  • Organometallic Compounds / chemistry
  • Pentetic Acid / chemistry*
  • Peptides, Cyclic / chemical synthesis*
  • Peptides, Cyclic / chemistry

Substances

  • Indium Radioisotopes
  • Organometallic Compounds
  • Peptides, Cyclic
  • cyclo(Arg-Gly-Asp-Phe-Lys)(2)DTPA
  • cyclo(Arg-Gly-Asp-Phe-Lys)DTPA
  • Pentetic Acid