Speciation 98: Abstracts

Cu(II) Co-Ordination by a-Hydroxymethylated Deltakephalin

J. Szyrwiel,1 W. Lesniak,1 T. Kowalik-Jankowska,1 M. Stasiak,2 and M.T. Leplawy

1 Faculty of Chemistry, University of Wroclaw, 50-383 Wroclaw, Poland;
2 Institute of Organic Chemistry, Technical University, Lódz, Poland

Deltakephalin is a hexapeptide, Tyr-D-Thr-Gly-Phe-Leu-Thr, very selectively inter-acting with d-opioid receptor. Our earlier studies have shown that enkephalins and their analogues are very efficient and highly specific ligands for Cu2+ ions.1,2 Insertion of the a-hydroxymethylserine (HMS) into the peptide sequence causes the distinct gain in the efficiency in the metal ion co-ordination and its specificity.3 In this work we have studied the effect of the a-hydroxymethylserine substitutions into the deltakephalin sequence on the binding ability towards Cu2+ ions. The effects of Cu2+ on the biological activity of this type of peptides have also been demonstrated (see refs. in 3). The potentiometric and spectroscopic data allow to establish the speciation in deltakephalin and its two analogues containing HMS residue in the second position, and second and six positions. The comparison of the stability constants of Cu2+ with three peptides clearly indicate that substitution of HMS increases distinctly the binding ability of peptide ligand. This is particularly well seen when HMS was inserted in position two and six (Table 1, Fig. 1).


Fig.1

Tabele1
peptideslogb011 logb012logb013 logb111logb101 logb1-11 logb1-21logb1-31
1) Tyr-D-Thr-Gly-Phe-Leu-Thr 9,9417,19 20,5414,35 9,513,18 -5,42-15,58
2) Tyr-HmS-Gly-Phe-Leu-Thr 9,7616,90 20,3713,90 9,663,77 -4,61-14,71
3) Tyr-HmS-Gly-Phe-Leu-HmS 9,6516,86 20,1814,84 10,034,46 -4,02-13,75

References

  1. G.Formicka-Kozlowska, L.D.Pettit, I.Steel, C.E.Livera, G.Kupryszewski, K.Rolka, J.Inorg.Biochem., 24, 299, (1985)
  2. T.Kowalik-Jankowska, Ch.O.Onindo, H.Kozlowski, L.D.Pettit, L.Lankiewicz, M.Jasionowski, J.Inorg.Biochem., 60, 21, (1995)
  3. T.Kowalik-Jankowska, M.Stasiak, M.T.Leplawy, H.Kozlowski, J.Inorg.Biochem., 66, 193, (1997)

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