STUDIES ON THE OXIDASE PROPERTIES OF CERULOPLASMIN: FACTORS IN NORMAL AND WILSON'S-DISEASE SERUM AFFECTING OXIDASE ACTIVITY

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Abstract
Purified human ceruloplasmin solution has been mixed with 27 normal sera and with 23 sera from patients with Wilson''s disease in the proportions 1:3, 2:2, and 3:1; the effect on oxidase activity was studied. The normal serum: ceruloplasmin mixtures showed potentiation of oxidase activity in all proportions. The addition of ceruloplasmin to Wilson s disease serum resulted in inhibition of oxidase activity in the 3:1 and 2:2 mixtures and very slight potentiation in the 1:3 mixture. The difference from normal serum is statistically significant for all 3 dilutions. The serum of patients with hepatic cirrhosis of other etiologies behaved as did normal serum. Protein-free filtrate of plasma from normal individuals and patients with Wilson s disease inhibited the oxidase activity of ceruloplasmin strongly. The residual protein from normal serum behaved as did whole normal serum. The residual protein from the Wilson''s disease serum inhibited the oxidase activity of ceruloplasmin to the same extent as whole Wilson s disease serum. Apoceruloplasmin and whole serum from which ceruloplasmin Cu had been removed by dialysis at pH 3 both inhibited normal ceruloplasmin and ceruloplasmin in whole normal serum to the same extent as did Wilson s disease serum. An apoceruloplasmin may be present in the serum of patients with Wilson''s disease and such a protein could not be detected by estimating either absorption at 605 mu or by determining oxidase activity.