酸性溶液中におけるTetracycline類のCu^<2+>への配位

概要

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The coordination sites of tetracyclines to Cu^<2+> in a solution at pH 5 were examined by the methods of circular dichroism (CD) spectra, absorption spectra and optical rotation. The results obtained were as follows : 1) The CD spectrum of tetracycline (TC)-Cu^<2+> complex showed a positive peak at 400 nm, whereas that of tetracyclinenitrile (TN)-Cu^<2+> complex didn't show any positive peaks in the range over 350 nm. 2) Bathochromic shifts in the absorption spectra of TC and TN induced by the addition of Cu^<2+> at pH 5 were observed. 3) With an increase in the molar ratio of Cu^<2+> to TC or oxytetracycline (OT), the optical rotation changed from negative to positive. On the other hand, the optical rotation of TN-Cu^<2+> complex was independent of the molar ratio of Cu^<2+> to TN. 4) The CD spectrum of TC-Cu (ethylenediamine)^<2+> or OT-Cu (ethylenediamine)^<2+> complex showed a positive peak at 400 nm or 390 nm. 5) The curves obtained by the plots of the optical rotation against the molar of Cu (ethylenediamine)^<2+> to TC or OT were similar to that obtained by the plots against the molar ratio of Cu^<2+> to OT. Therefore, at pH 5,tetracyclines may bind to Cu^<2+> at both C_<11>-C_<12> β-diketone site and C_2 carboxamide site through bending of A ring over B and C rings.
公益社団法人日本薬学会の論文
1981-02-25