Decomposition and superoxide dismutase activity of the copper complex of D-penicillamine (Cu(II)6Cu(I)8 (D-penicillamine)12 Cl)5− |
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Authors: | Ulrich Deuschle Ulrich Weser |
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Institution: | Anorganische Biochemie, Physiologisch-chemisches Institut der Universität Tübingen, D-7400 Tübingen, Hoppe-Seyler Strasse 1, F.R.G. |
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Abstract: | The possible time- and/or light-dependent decomposition of the purple Cu(I), Cu(II)-complex of D-penicillamine (Cu(II)6Cu(I)8(D-penicillamine)12Cl)5? was examined. Superoxide dismutase activity of the freshly prepared complex was assayed using the nitroblue tetrazolium assay. The formazan colour formation was inhibited by 50% in the presence of approximately 500 μM copper. Ageing of the copper complex, especially in the light, resulted in a marked increase of EDTA-sensitive activity. Upon gel chromatography of the aged samples the original low inhibitory activity was restored. All EDTA-sensitive inhibitory activity was found in a clearly separated low Mr copper-containing fraction. Aerobic irradiation with a tungsten lamp at 30 °C accelerated the decomposition of (Cu(II)6Cu(I)8(D-penicillamine)12Cl)5?. ?Cu518 = 1800 M?1 cm?1 dropped to ?Cu640 = 60 M?1 cm?1. The photochemical conversion of (Cu(II)6? Cu(I)8(D-penicillamine)12Cl)5? was complete within 48 h. Due to the identical electronic absorption profile of both, the decomposition product and Cu(II) D-penicillamine disulphide the latter complex was assigned to be the unknown low Mr copper-compound. Circular dichroism and electron paramagnetic resonance measurements support this conclusion. |
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Keywords: | Author to whom correspondence should be addressed |
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