Biotin

Biotin, or vitamin B7, is a water-soluble vitamin that enzymes use to transfer carbon dioxide in fatty-acid synthesis and other metabolic reactions.

Carboxylation: A chemical reaction that adds a carboxyl group to a molecule. Biotin-dependent enzymes use this reaction to add carbon dioxide to metabolic substrates.
B vitamins: A group of water-soluble vitamins that support metabolism and other cellular functions. Biotin is one member of this family, historically designated vitamin B7.
Biotin deficiency: A rare nutritional or metabolic condition caused by inadequate biotin availability. It reveals the consequences of impaired biotin supply or recycling for human metabolism.
Vitamin: An organic nutrient required in small amounts for normal growth and physiological function. Biotin’s recognition as a vitamin followed evidence that animals need it in their diet.
Biotin-dependent carboxylase: An enzyme that uses biotin to transfer carbon dioxide to a substrate. These enzymes bind biotin and coordinate its movement between two catalytic sites.
Cofactor: A nonprotein substance required for an enzyme to carry out its function. Biotin is the organic cofactor that enables several enzymes to catalyze carboxylation.
Biotinidase deficiency: An inherited disorder that prevents efficient recycling of biotin from biocytin and dietary proteins. This treatable cause of biotin deficiency demonstrates why biotin recycling matters.
Paul György: A Hungarian-born biochemist who identified vitamins B6 and H and studied vitamin deficiency diseases. His research helped establish biotin as the vitamin later called B7.
Biotin protein ligase: An enzyme that attaches biotin covalently to specific lysine residues in proteins. It activates biotin-dependent enzymes by linking biotin to their carrier domains.
Coenzyme: An organic molecule that assists an enzyme by carrying atoms, electrons, or chemical groups. Biotin acts as a tightly bound coenzyme that carries activated carbon dioxide.

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