A description of an HPLC assay of coproporphyrinogen III oxidase activity in mononuclear cells

Coproporphyrinogen III oxidase is deficient in hereditary coproporphyria. An activity assay for this enzyme in mononuclear cells, besides the preparation of the substrate, are presented. The separation conditions for the product of the test protoporphyrin IX by gradient, reversed-phase high-performance liquid chromatography are given. The normal value from mononuclear cells of healthy volunteers was 138±21 pkat/g total soluble protein (mean±SD). The enzyme activity of a family with hereditary coproporphyria was measured. The gene carriers exhibit a specific coproporphyrinogen III oxidase activity of 61–90 pkat/g total soluble protein.