Amino acid homologies between human biotinidase and bacterial aliphatic amidases: putative identification of the active site of biotinidase.

A search of protein databases revealed amino acid homologies among human biotinidase, bacterial aliphatic amidases, and bacterial and plant nitrilases. Amino acids YRK(210-212) of biotinidase are conserved among the enzyme families. This homology and naturally occurring mutations that cause biotinidase deficiency suggest that this region is essential for enzyme activity and is conserved from bacteria. Cys(245) is likely the cysteine in the active site of biotinidase.