Biotinidase deficiency: the possible role of biotinidase in the processing of dietary protein-bound biotin.

Abstract

Biotinidase (EC 3.5.1.12) cleaves covalently-bound biotin from partially degraded carboxylases and from biocytin, thereby recycling biotin. We have recently demonstrated that the activity of biotinidase is deficient in serum from children with late-onset multiple carboxylase deficiency (Wolf et al., 1983a, b). Using a newly developed, sensitive radioassay, we have shown that biotinidase activity is also deficient in peripheral blood leukocytes and fibroblasts of affected patients (Wolf and McVoy, 1984). The enzyme activities in the parents of these children are intermediate between deficient and normal values. These findings indicate that the primary enzyme defect in late-onset multiple carboxylase deficiency is in biotinidase activity and that the disorder is inherited as an autosomal recessive trait. Children lacking biotinidase activity are unable to recycle biotin and depend on exogeneous biotin to prevent the clinical and biochemical features of biotin deficiency. Although previous reports have described’ impaired’ intestinal absorption of free biotin in patients with late-onset multiple carboxylase deficiency, the absorption of free biotin was found to be normal in one of these patients when loading studies were repeated while her tissues were not biotin-depleted. Moreover, this patient was found to be biotinidase deficient (Thoene and Wolf, 1983). Because there is considerable clinical variability in this disorder (Wolf et al., 1983c) and the concentrations of free and protein-bound biotin in foods are variable, biotinidase may also play a critical role in the processing of dietary protein-bound biotin.KeywordsPancreatic JuiceBiotinidase DeficiencyAutosomal Recessive TraitBiotinidase ActivityBiotin DeficiencyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.