Binding ability of N-para-amino-phenylsulfonyl and N-para-nitro-phenylsulfonyl derivatives of amino acids and dipeptides

METALS IN MEDICINE 229

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BINDING ABILITY OF N-PARA-AMINO-PHENYLSULFONYL AND N-PARA-NITRO-PHENYLSULFONYL DERIVATIVES OF AMINO ACIDS AND DIPEPTIDES. T. Kowalik-Jankowska

a Institute of Chemistry, University of WrocSaw, Fdoliot-Curie 14, 50-383 Wroc3aw, Poland; All the effective antibacterial sulfonamides are derivatives of sulfanilamide. Although the usefulness of these compounds was considerably limited by the introduction of more efficient antibiotics, recent developments in the application of their metal complexes in burn therapy has revived interest in sulfanilamides and their metal complexes. The coordination ability of amino acids (Gly, Ala, Val, Glu) and dipeptides ( Ala-Ala, Ala-His) substituted on the N-terminal amino group with para-amino-phenylsulfonyl (PAS) and para-nitro-phenylsulfonyl (PNS) groups were studied with potentiometric and spectroscopic ( absorption uv/vis, c.d. and e.p.r, spectra) techniques. The para substituent of phenylsulfonyl moiety have very strong impact on sulfonamide nitrogen acidity. Usually amide nitrogen is unable to act as an anchor site, however, sulfonamide nitrogen having pK between 9 and 11 does not need any anchoring binding group to form complexes with copper(II) ions. The amino acids derivatives (PAS, PNS) are very effective ligands for Cu(II) ions. The copper(II) ions are able to deprotonate and bind to sulfonamide nitrogen below pH 5 to form stable mono- and bis-{N'sulf, COO-} chelates [1]. PAS-Ala-AIa and PNS-Ala-AIa behave as the dipeptide molecules with free Nterminal amino group. The CuH.1L {Nsulf-,Npep',COO'} and CuH_2L {Nsulf', eP', COO-, OH-} complexes are formed. PAS or PNS moieties change considerably the coordination eqilibria of Ala-His unit when compare to parent dipeptide [2]. Both groups force the formation of the dimeric Cu2H_2L 2 complexes, while in the case of the parent dipeptides the major species are only monomeric species. 1. T. Kowalik-Jankowska, H. Kozlowski, L.D. Pettit, K. Pawelczak, M. Makowski, J.Inorg.Biochem.,57,183(1995). 2. T. Kowalik-Jankowska, H. Kozlowski, K. Pawelczak, M. Makowski, submitted to publication.