Protoporphyrinogen oxidase and porphobilinogen deaminase in variegate porphyria |
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| Authors: | P N MEISSNER R S DAY M R MOORE† P B DISLER‡ E HARLEY§ |
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| Institution: | MRC Liver Research Group, Department of Medicine, University of Cape Town, Observatory, 7925, South Africa;*MRC Institute for Biostatistics, P.O. Box 70, Tygerberg, 7505, Cape Town;?University of Glasgow, Department of Medicine, Gardiner Institute, Western Infirmary, Glasgow G11 6NT, Scotland;?Departments of Community Health, University of Cape Town, South Africa;§Chemical Pathology, University of Cape Town, South Africa |
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| Abstract: | Abstract. Two enzymes of the haem biosynthetic pathway were investigated in patients with variegate porphyria. Protoporphyrinogen oxidase in cultures of Epstein-Barr virus transformed lymphoblasts from twenty-seven patients showed a mean maximal velocity ( V max) of 0·39 ± 0·08+ nmol of protoporphyrin mg protein-1 h-1, a 52% reduction ( P < 0·001) from a non-porphyric control group (0·82 ± 0·10). K m values (1·00 ± 0·27 μ M) did not differ significantly ( P > 0·05) from control values in any of the patients. The mean V max of porphobilinogen deaminase in the cultures was 1·50 ± 0·18 nmol of uroporphyrin mg protein-1 min-1, a 24% reduction ( P < 0·001) from controls (1·94 ± 0·14). Mean porphobilinogen deaminase activity in the erythrocytes of twenty-one patients with variegate porphyria was 8·37 ± 1·99 nmol of uroporphyrin 1 erythrocytes-1 s-1, a 28% reduction ( P < 0·001) from normal (11·98 ± 2·11). The reduced activities of these two enzymes comply with the expression of variegate porphyria during its quiescent and acute phases. |
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| Keywords: | Variegate porphyria propoporhyrinogen oxidase |
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