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Models for blue copper proteins: Copper(II)-disulfide interaction in some copper complexes containing salicyl-, pyridyl-, and imidazolyl-aldimine ligands.
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A bstracts
co51
MODELS FOR BLUEiCOPPER PROTEINS: COPPRR(II)DISULPIDE INTERACTION IN SOME COPPER COMPLEXES CCjNTAININGSALICYL-, PYRIDYKr, AND IMIPAZOLYL-ALDIMTNE LIGANDS.
The disulfide sulfur has been postulated to be involved in binding to copper in stellscyanin, a With an aim TV understand type I copper protein~ll. the mode of Cu(I.I)-disulfide interaction, &III) complexes of Schiff base ligands formed by the condensation of cystamine (CYST or 2,2'--diaminodiphenyldisul.fide(DDDS) with salicylaldehyde(SAL), pyridine-Z-carboxaldehyde(PY1 and imidazole- :'?-carbox aldehyde(IM) and also of the reduced form of these Schiff bases have been isoLatedC21. The isolation of CYS-- derived PY complexes was unsuccessful. The electronic spectra of CYS- and PDDS-derived SAL complexes exhibit a single LF band aro~lnd 15.5 and 17.5 kK respectively and S(a) ---? CujII! and S(n) --> Cu(I1) CT bands around 28.5 and 23.8 kK respectively_ The IM incorporated DDDS-CW 11: complexes exhibit a shoulder around 19,5 kK and a CT band around 29 kK whereas the PY incorporated ones exhibit a highly intense visible band around 18.5 kK (G>250Q) along with a CT band of far greater intensity at *- 30.0 kK (1,16,000? supporting zin intensity stealing mechanism f3l. All the compounds exhibit irreversible redox behaviour at a platinum sphere electrode. Relatively low A values are observed and the positive redox potentials (0.5 to 0-7 V Vs NHE) lie in the range displayed by the protein blue sites. The -delocalisation and the ligand unsaturation affect the LF, CT and EPR parameters as well as the sedox potentials. All these results are consistent with an equatorial Cu(ITj-disulfide interaction. 1. 2. 3.
0. Farver and I. Pecht, Inos-g- ChemWq 29. 4855 (19901. 0. Yamauchi, H, Seki and T. Shoda, BuI.~, Chem- 5bc, cJp"=, 56, 3260 (1983). D. E. Nikles, M. J. Powers and F. L_ Urbach, 1narg. Chem., 22, 3213 (1983?_
A bstracts
co51
MODELS FOR BLUEiCOPPER PROTEINS: COPPRR(II)DISULPIDE INTERACTION IN SOME COPPER COMPLEXES CCjNTAININGSALICYL-, PYRIDYKr, AND IMIPAZOLYL-ALDIMTNE LIGANDS.
The disulfide sulfur has been postulated to be involved in binding to copper in stellscyanin, a With an aim TV understand type I copper protein~ll. the mode of Cu(I.I)-disulfide interaction, &III) complexes of Schiff base ligands formed by the condensation of cystamine (CYST or 2,2'--diaminodiphenyldisul.fide(DDDS) with salicylaldehyde(SAL), pyridine-Z-carboxaldehyde(PY1 and imidazole- :'?-carbox aldehyde(IM) and also of the reduced form of these Schiff bases have been isoLatedC21. The isolation of CYS-- derived PY complexes was unsuccessful. The electronic spectra of CYS- and PDDS-derived SAL complexes exhibit a single LF band aro~lnd 15.5 and 17.5 kK respectively and S(a) ---? CujII! and S(n) --> Cu(I1) CT bands around 28.5 and 23.8 kK respectively_ The IM incorporated DDDS-CW 11: complexes exhibit a shoulder around 19,5 kK and a CT band around 29 kK whereas the PY incorporated ones exhibit a highly intense visible band around 18.5 kK (G>250Q) along with a CT band of far greater intensity at *- 30.0 kK (1,16,000? supporting zin intensity stealing mechanism f3l. All the compounds exhibit irreversible redox behaviour at a platinum sphere electrode. Relatively low A values are observed and the positive redox potentials (0.5 to 0-7 V Vs NHE) lie in the range displayed by the protein blue sites. The -delocalisation and the ligand unsaturation affect the LF, CT and EPR parameters as well as the sedox potentials. All these results are consistent with an equatorial Cu(ITj-disulfide interaction. 1. 2. 3.
0. Farver and I. Pecht, Inos-g- ChemWq 29. 4855 (19901. 0. Yamauchi, H, Seki and T. Shoda, BuI.~, Chem- 5bc, cJp"=, 56, 3260 (1983). D. E. Nikles, M. J. Powers and F. L_ Urbach, 1narg. Chem., 22, 3213 (1983?_