Biotinidase (BTD)

Biotinidase is an enzyme (EC 3.5.1.12) encoded by the BTD gene located on chromosome 3p25, responsible for cleaving biotin (vitamin H) from biocytin (biotinyl-lysine) and from biotin-bound peptides, thus recycling biotin for reuse as a cofactor by carboxylase enzymes involved in the metabolism of fats, carbohydrates, and proteins[1][5]. Its deficiency, inherited in an autosomal recessive manner, results in impaired biotin recycling, leading to multiple carboxylase deficiency with neurocutaneous and metabolic manifestations, but can be effectively treated and prevented by oral biotin supplementation[2][5]. The enzyme is a glycoprotein with multiple isoforms and glycosylation sites, exhibits a catalytic triad (glutamate, lysine, cysteine), and acts primarily in tissues with high metabolic demand including liver and brain[3][5]. Biotinidase deficiency is included in newborn screening programs due to the severity but treatability of disease upon early detection[5][7].

Other names

biotinaseamidohydrolase biotinidasebiotin-amide amidohydrolase

Biotin supplementation compensates for endogenous enzyme deficiency by providing free biotin that bypasses the need for biotin release by biotinidase