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A circular dichroic study of Cu(II) binding to bovine α-lactalbumin

1991; Elsevier BV; Volume: 42; Issue: 2 Linguagem: Inglês

10.1016/0162-0134(91)80038-j

1873-3344

E. Tieghem, H. Van Dael, Frans Van Cauwelaert,

Molecular Sensors and Ion Detection

The visible and ultraviolet circular dichroic spectra resulting from the interaction of bovine α-lactalbumin with successive Cu(II) ions have been recorded under a variety of conditions. Analysis of the observed charge-transfer and d-d band transitions can be made in terms of two kinds of binding sites: at a histidyl group and at the N-terminal amino group, respectively. At basic pH the amide nitrogens of the peptide backbone progressively take part in the coordination. The occupation of the high affinity calcium binding site by Ca(II) and Mn(II) does not influence the Cu(II) binding process, suggesting that there is no direct interaction between this site and the Cu(II) binding sites.