Sulfhydryl Groups in the Reconstitution of Ceruloplasmin

Binding of transition metal ions by ceruloplasmin (ferroxidase)

“…ions bound by approximately one suggests that these ions also can bind to this site. It has been shown that, depending on conditions, there may be one accessible SH group in ceruloplasmin (Witwicki and Zakrzewski, 1969;Erickson et al, 1970). Since there is one "Chelexable site" per molecule, this might reflect the reactivity of the metal ions with this SH site, an idea that might be confirmed by the preparation of specific SH derivatives.…”

Interactions of histidine and other imidazole derivatives with transition metal ions in chemical and biological systems

“…Removal of copper to give the apoenzyme results in five to six more titratable groups in the range of pH 7, i.e., in the range of the imidazole ring.284 Photooxidation, which results in preferential destruction of histidine residues, destroys the oxidase activity of the enzyme and facilitates loss of copper by the enzyme.285 There is also apparently a correlation between iodination of histidine residues and loss of oxidase activity, when the protein is subjected to iodination.286 Other studies point strongly to sulfhydryl groups at the copper binding site in ceruloplasmin. 287 Histidine may act as a ligand in the oxygen carrying Cu(I) protein hemocyanin. The copper binding ability of hemocyanin is diminished in parallel with histidine photooxidation or diazo coupling, from which the inference that histidine is responsible for copper binding can be drawn.288 Titration data have also formed the basis for the same suggestion.289 The correspondence noted between the circular dichroism of oxyhemocyanln and the Cu(II) complexes of histidyl containing peptides290 is probably overdrawn.…”

Ferritin does not accumulate iron oxidized by caeruloplasmin

“…Its concentration was calculated from its absorbance at 610 nm (Al M = 10.9) [13]. Apo-Cp was prepared as described in [14].…”