Electron paramagnetic resonance and ultraviolet-visible spectroscopic evidence for copper porphyrin in actinomycete melanins |
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| Authors: | A. S. Mangrich A. W. Lermen E. J. Santos R. C. Gomes R. R. R. Coelho L. F. Linhares N. Senesi |
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| Affiliation: | (1) LABEPR Departamento de Química, UFPR, 81531-970, CP 19081, Curitiba, Brasil, XX;(2) Instituto de Tecnologia do Paraná, 81531-970, Curitiba, Brasil, XX;(3) Instituto de Microbiologia Prof. Paulo de Góes, UFRJ, CCS, Bl I, Ilha do Funda~o, 21941-590, Rio de Janeiro, Brasil, XX;(4) Istituto di Chimica Agraria, Università di Bari, Via Amendola, 165/A, I-70126 Bari, Italy Tel: +39-80-5442853; Fax: +39-80-5442813; e-mail: nsenesi@mail2.clio.it, IT |
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| Abstract: | The coordination chemistry of iron (III) (Fe3+) and copper (II) (Cu2+) in melanins synthesized by seven actinomycetes isolated from Brazilian latosol soils under savanna (cerrado) vegetation was investigated using electron paramagnetic resonance (EPR) and ultraviolet-visible (UV-Vis) spectroscopy. The EPR spectra indicated the presence of Cu2+ ions bound to oxygenated and nitrogenous functional groups, and rhombic coordinated Fe3+ ions. In some of the actinomycete melanins the EPR hyperfine splitting of Cu+2 ion complexes was well resolved, and indicated four magnetically equivalent nitrogen atoms in a plane. This result suggested the presence of Cu+2 porphyrin complexes, which was confirmed by Soret bands in the 400-nm region of the UV-Vis spectra. The concentration of Mn in actinomycete melanins, determined by inductively coupled plasma atomic emission spectroscopy, was lower than those of Cu and Fe. Received: 9 April 1997 |
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| Keywords: | Copper porphyrin Actinomycete melanins Electron paramagnetic resonance spectroscopy Brazilian soils |
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