[Allosteric regulation of ceruloplasmin activity].

Study of the interactions of homogenous human ceruloplasmin preparations with histamine show that the rate of p-phenylene diamine oxidation by ceruloplasmin is increased in the presence of histamine; the increase in the enzyme activity is independent of histamine concentration. The dependence of the reaction rate on substrate concentration is S-shaped, both in the presence and in the absence of histamine. The respective values of the Hill coefficient and Rs for the enzyme in the presence and in the absence of histamine are 2.