biotinidase
Last updated 20 May 2021
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The BTD gene provides instructions for making an enzyme called biotinidase. This enzyme recycles biotin, a B vitamin found in foods such as liver, egg yolks, and milk. Biotinidase removes biotin that is bound to proteins in food, leaving the vitamin in its free (unbound) state. The body needs free biotin to activate enzymes called biotin-dependent carboxylases. These carboxylases are involved in many critical cellular functions, including the breakdown of proteins, fats, and carbohydrates.
Normal function
The BTD gene provides instructions for making an enzyme called biotinidase. This enzyme recycles biotin, a B vitamin found in foods such as liver, egg yolks, and milk. Biotinidase removes biotin that is bound to proteins in food, leaving the vitamin in its free (unbound) state. The body needs free biotin to activate enzymes called biotin-dependent carboxylases. These carboxylases are involved in many critical cellular functions, including the breakdown of proteins, fats, and carbohydrates.
In addition to processing biotin obtained from the diet, biotinidase recycles biotin within the body. As biotin-dependent carboxylases are broken down, they release a molecule called biocytin. Biocytin is a complex made of up biotin and a protein building block (amino acid) called lysine. Biotinidase splits this complex, making free biotin available for reuse by other carboxylase enzymes.
Researchers suspect that biotinidase may have several additional functions. This enzyme may transport free biotin through the bloodstream. It might also have the ability to attach biotin to certain proteins through a process called biotinylation. Within the nucleus, biotinylation of DNA-associated proteins called histones may help determine whether certain genes are turned on or off. It is unclear, however, whether biotinidase plays a role in regulating gene activity.
Conditions referring to this gene or chromosome
Other names
Biocytin Hydrolase
Further reading and references
- biotinidase; MedlinePlus, National Library of Medicine.
- Dobrowolski SF, Angeletti J, Banas RA, Naylor EW. Real time PCR assays to detect common mutations in the biotinidase gene and application of mutational analysis to newborn screening for biotinidase deficiency. Mol Genet Metab. 2003 Feb;78(2):100-7. doi: 10.1016/s1096-7192(02)00231-7.
- Hymes J, Stanley CM, Wolf B. Mutations in BTD causing biotinidase deficiency. Hum Mutat. 2001 Nov;18(5):375-81. doi: 10.1002/humu.1208.
- McMahon RJ. Biotin in metabolism and molecular biology. Annu Rev Nutr. 2002;22:221-39. doi: 10.1146/annurev.nutr.22.121101.112819. Epub 2002 Jan 4.
- Wolf B, Jensen KP, Barshop B, Blitzer M, Carlson M, Goudie DR, Gokcay GH, Demirkol M, Baykal T, Demir F, Quary S, Shih LY, Pedro HF, Chen TH, Slonim AE. Biotinidase deficiency: novel mutations and their biochemical and clinical correlates. Hum Mutat. 2005 Apr;25(4):413. doi: 10.1002/humu.9329.
- Wolf B. Biotinidase deficiency: "if you have to have an inherited metabolic disease, this is the one to have". Genet Med. 2012 Jun;14(6):565-75. doi: 10.1038/gim.2011.6. Epub 2012 Jan 5.
- Wolf B. Biotinidase: its role in biotinidase deficiency and biotin metabolism. J Nutr Biochem. 2005 Jul;16(7):441-5. doi: 10.1016/j.jnutbio.2005.03.024.
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