Abstract
Biotinidase cleaves biotin from biocytin (ε-N-biotinyllysine) and biotinyl-peptides resulting from the degradation of carboxylases and, consequently, is important in recycling the vitamin. Some of the variability in the clinical features and age of onset of biotinidase deficiency (ranges from 3 weeks to several years) may be a consequence of differences not only in the total dietary biotin consumption but also in the form of the vitamin in the diet. Biotinidase-deficient children whose diets contain foods rich in free (as opposed to protein-bound) biotin may take longer to become biotin-deficient and, hence, to manifest the signs and symptoms of biotinidase deficiency. We have shown that biotinidase activity in rats is not enriched in intestinal brush border membranes but it is present in mucosa from all sections of the small intestine, and it is also in pancreatic homogenates (24.0±5.5 pmol/min/mg protein), isolated secretory granules (6.3 pmol/min/mg) and pancreatic juice from cannulated ducts (316±189 pmol/min/ml or 7.0±4.2 pmol/min/mg). The apparent Km of N-biotinyl-p-aminobenzoate (an artificial substrate) for biotinidase was 10 μM and broad pH optima of 4 to 8 were observed for enzymes from both rat serum and pancreatic juice. These findings suggest that biotinidase has an important role in increasing the bioavailability of dietary biotin.
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Heard, G., Wolf, B. & Reddy, J. PANCREATIC BIOTINIDASE ACTIVITY: THE POTENTIAL FOR INTESTINAL PROCESSING OF DIETARY PROTEIN-BOUND BIOTIN. Pediatr Res 18 (Suppl 4), 198 (1984). https://doi.org/10.1203/00006450-198404001-00633
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DOI: https://doi.org/10.1203/00006450-198404001-00633
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