Proton NMR investigation of Ln3+ complexes of thymopoietin32-36

Joseph B. Vaughn, Richard L. Stephens, Robert E. Lenkinski, N. Rama Krishna, George A. Heavner, Gideon Goldstein

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1 Scopus citations


The pentapeptide Arg-Lys-Asp-Val-Tyr (TP5) is a biologically active fragment of thymopoietin, the thymic hormone that induces selective T-cell differentiation. The formation of lanthanide(III) complexes of TP5 is demonstrated through the observation of Tb3+ fluorescence enhancement. The equilibria, stoichiometry and solution conformation of the La3+, Pr3+ and Yb3+ complexes of TP5 have been investigated using NMR spectroscopy. In addition, the dissociation constants of two methyl ester analogs of TP5 have been studied. Evidence is presented supporting an interaction between the arginine guanidino Nε{lunate}H and the aspartate carboxylate of TP5. Binding of Ln3+ appears to be accompanied by a disruption (or weakening) of this interaction and a concomitant increase in the 180° rotamer population for the aspartate carboxylate group. The observed trends in the magnitudes of the dissociation constants and the rotamer populations appear to suggest that, although a significant amount of monodentate complexes may also exist, the metal ion binds predominantly to both carboxylates in a bidentate fashion.

Original languageEnglish (US)
Pages (from-to)50-60
Number of pages11
JournalBBA - Protein Structure
Issue number1
StatePublished - Nov 30 1981


  • H-NMR
  • Ln complex
  • Thymopoietin

ASJC Scopus subject areas

  • Medicine(all)


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