Biotin is an important cofactor for carboxylase enzymes. As the name sounds, these enzymes add carboxylic acid groups (-COOH) to whatever compound they act on. In fatty acid synthesis, biotin is required by the enzyme that forms malonyl CoA from acetyl-CoA, as shown below1.
Another biotin-requiring carboxylase is one that converts pyruvate to oxaloacetate in gluconeogenesis as shown below1.
In addition to these two functions, biotin is also important for histone biotinylation and the breakdown of isoleucine, leucine, methionine, and threonine1.
Histone biotinylation is an epigenetic modification that is described in the next section.
Biotin is an effective treatment for brittle nail syndrome, but it has not been shown to improve healthy nails4. There is little evidence to suggest that biotin improves healthy hair as well5.
References & Links
1. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
4. Scheinfeld N, Dahdah MJ, Scher R. (2007) Vitamins and minerals: their role in nail health and disease. 6(8): 782-787.
5. Famenini S, Goh C. (2014) Evidence for supplemental treatments in androgenetic alopecia. 13(7): 809-812.