Biotin is a vitamin that is a cofactor for enzymes involved in carbon dioxide metabolism. Biotin‐dependent enzymes catalyse carboxylations, decarboxylations and transcarboxylations. These reactions are involved in a variety of metabolic functions from fatty acid synthesis to gluconeogenesis and are found in all animals, plants and bacteria. The common feature of biotin‐dependent enzymes is they are multifunctional. They contain two separate active sites that catalyse distinct chemical reactions. The biotin moiety, which is covalently attached to the enzyme via the amino acid lysine, alternates between the two distinct active sites. In one active site, biotin is carboxylated, whereas, in the other active site, the carboxyl group is transferred to an acceptor molecule. Avidin and streptavidin are proteins that bind biotin very tightly. The high affinity between biotin and avidin/streptavidin is utilised for a variety of biotechnological techniques such as protein purification and immunoassays such as Western blotting.

Key Concepts

  • Biotin is a vitamin.

  • Biotin is a cofactor for enzymes involved in CO2 metabolism.

  • Biotin‐dependent enzymes catalyse carboxylation, decarboxylation and transcarboxylation reactions.

  • Biotin‐dependent enzymes are multifunctional and contain two distinct active sites.

  • Biotin, which is covalently attached to a protein, moves between each of the two active sites.

  • The two active sites and the biotin carrier protein can comprise three separate proteins that form a complex or they can form domains on a single polypeptide.

  • The biotin‐dependent enzyme acetyl‐CoA carboxylase is an emerging target for antibiotic development.

  • The proteins avidin and streptavidin bind biotin very tightly and with a high degree of specificity.

  • The very high affinity and specificity of the biotin avidin/streptavidin interaction is used for many biotechnology techniques.

Keywords: carboxylase; decarboxylase; transcarboxylase; avidin; streptavidin

Figure 1. Structure of biotin.
Figure 2. Amino acids of streptavidin that bind with biotin.
Figure 3. Schematic illustrating biotin–avidin interactions in the development of biotechnical applications.


Athappilly FK and Hendrikson WA (1995) Structure of the biotinyl domain of acetyl‐coenzyme A carboxylase determined by MAD phasing. Structure 3: 1407–1419.

Bilder P, Lightle S, Bainbridge G, et al. (2006) The structure of the carboxyltransferase component of acetyl‐coA carboxylase reveals a zinc‐binding motif unique to the bacterial enzyme. Biochemistry 45: 1712–1722.

Broussard TC, Kobe MJ, Pakhomova S, et al. (2013) The three‐dimensional structure of the biotin carboxylase‐biotin carboxyl carrier protein complex of E. coli acetyl‐CoA carboxylase. Structure 21: 650–657.

Chapman‐Smith A and Cronan JE (1999) The enzymatic biotinylation of proteins: a post‐translational modification of exceptional specificity. Trends in Biochemical Sciences 24: 359–363.

Chapman‐Smith A, Turner DL, Cronan JE, Morris TW and Wallace JC (1994) Expression, biotinylation and purification of a biotin‐domain peptide from the biotin carboxy carrier protein of Escherichia coli acetyl‐CoA carboxylase. Biochemical Journal 302: 881–887.

Cheng CC, Shipps GW Jr, Yang Z, et al. (2009) Discovery and optimization of antibacterial AccC inhibitors. Bioorganic & Medicinal Chemistry Letters 19: 6507–6514.

Cho YS, Lee JI, Shin D, et al. (2008) Crystal structure of the biotin carboxylase domain of human acetyl‐CoA carboxylase 2. Proteins 70: 268–272.

Cronan JE and Waldrop GL (2002) Multi‐subunit acetyl‐CoA carboxylases. Progress in Lipid Research 41: 407–435.

Diacovich L, Mitchell DL, Pham H, et al. (2004) Crystal structure of the beta‐subunit of acyl‐CoA carboxylase: structure‐based engineering of substrate specificity. Biochemistry 43: 14027–14036.

Fan C, Chou CY, Tong L and Xiang S (2012) Crystal structure of urea carboxylase provides insights into the carboxyltransfer reaction. Journal of Biological Chemistry 287: 9389–9398.

Fawaz MV, Topper ME and Firestine SM (2011) The ATP‐grasp enzymes. Bioorganic Chemistry 39: 185–191.

Freiberg C, Brunner NA, Schiffer G, et al. (2004) Identification and characterization of the first class of potent bacterial acetyl‐CoA carboxylase inhibitors with antibacterial activity. Journal of Biological Chemistry 279: 26066–26073.

Green KD and Pflum MKH (2007) Kinase‐catalyzed biotinylation for phosphoprotein detection. Journal of the American Chemical Society 129: 10–11.

Hall PR, Wang YF, Rivera‐Hainaj RE, et al. (2003) Transcarboxylase 12S crystal structure: hexamer assembly and substrate binding to a multienzyme core. The EMBO Journal 22: 2334–2347.

Hall PR, Zheng R, Antony L, et al. (2004) Transcarboxylase 5S structures: assembly and catalytic mechanism of a multienzyme complex subunit. The EMBO Journal 23: 3621–3631.

Hamed RB, Batchelar ET, Clifton IJ and Schofield CJ (2008) Mechanisms and structures of crotonase superfamily enzymes‐‐how nature controls enolate and oxyanion reactivity. Cellular and Molecular Life Sciences 65: 2507–2527.

Huang CS, Sadre‐Bazzaz K, Shen Y, et al. (2010) Crystal structure of the alpha(6)beta(6) holoenzyme of propionyl‐coenzyme A carboxylase. Nature 466: 1001–1005.

Huang CS, Ge P, Zhou ZH and Tong L (2012) An unanticipated architecture of the 750‐kDa alpha6beta6 holoenzyme of 3‐methylcrotonyl‐CoA carboxylase. Nature 481: 219–223.

Kondo S, Nakajima Y, Sugio S, et al. (2007) Structure of the biotin carboxylase domain of pyruvate carboxylase from Bacillus thermodenitrificans. Acta Crystallographica Section D: Biological Crystallography 63: 885–890.

Lee CK, Cheong HK, Ryu KS, et al. (2008) Biotinoyl domain of human acetyl‐CoA carboxylase: Structural insights into the carboxyl transfer mechanism. Proteins 72: 613–624.

Livnah O, Bayer EA, Wilchek M and Sussman JL (1993) Three‐dimensional structures of avidin and the avidin–biotin complex. Proceedings of the National Academy of Sciences of the USA 90: 5076–5080.

Lombard J and Moreira D (2011) Early evolution of the biotin‐dependent carboxylase family. BMC Evolutionary Biology 11: 232.

Madauss KP, Burkhart WA, Consler TG, et al. (2009) The human ACC2 CT‐domain C‐terminus is required for full functionality and has a novel twist. Acta Crystallographica Section D: Biological Crystallography 65: 449–461.

Miller JR, Dunham S, Mochalkin I, et al. (2009) A class of selective antibacterials derived from a protein kinase inhibitor pharmacophore. Proceedings of the National Academy of Sciences of the USA 106: 1737–1742.

Mochalkin I, Miller JR, Evdokimov A, et al. (2008) Structural Evidence for Substrate‐Induced Synergism and Half‐Sites Reactivity in Biotin Carboxylase. Protein Science 17: 1706–1718.

Mochalkin I, Miller JR, Narasimhan L, et al. (2009) Discovery of antibacterial biotin carboxylase inhibitors by virtual screening and fragment‐based approaches. Chemical Biology 4: 473–483.

de Queiroz MS and Waldrop GL (2007) Modeling and numerical simulation of biotin carboxylase kinetics: implications for half‐sites reactivity. Journal of Theoretical Biology 246: 167–175.

Reddy DV, Shenoy BC, Carey PR and Sonnichsen FD (2000) High resolution solution structure of the 1.3S subunit of transcarboxylase from Propionibacterium shermanii. Biochemistry 39: 2509–2516.

Roberts EL, Shu N, Howard MJ, et al. (1999) Solution structures of apo and holo biotinyl domains from acetyl‐coenzyme A carboxylase of Escherichia coli determined by triple‐resonance nuclear magnetic resonance spectroscopy. Biochemistry 38: 5045–5053.

Shen Y, Volrath SL, Weatherly SC, Elich TD and Tong L (2004) A mechanism for the potent inhibition of eukaryotic acetyl‐coenzyme A carboxylase by soraphen A, a macrocyclic polyketide natural product. Molecular Cell 16: 881–891.

St Maurice M, Reinhardt L, Surinya KH, et al. (2007) Domain architecture of pyruvate carboxylase, a biotin‐dependent multifunctional enzyme. Science 317: 1076–1079.

Thoden JB, Blanchard CZ, Holden HM and Waldrop GL (2000) Movement of the biotin carboxylase B‐domain as a result of ATP binding. Journal of Biological Chemistry 275: 16183–16190.

Tong L (2013) Structure and function of biotin‐dependent carboxylases. Cellular and Molecular Life Sciences 70: 863–891.

Waldrop GL, Rayment I and Holden HM (1994) Three‐dimensional structure of the biotin carboxylase subunit of acetyl‐CoA carboxylase. Biochemistry 21: 1597–1619.

Waldrop GL, St. Maurice M and Holden HM (2012) The enzymes of biotin dependent CO2 metabolism: what structures reveal about their reaction mechanisms. Protein Science 33: 10249–10256.

Weber PC, Wendoloski JJ, Pantoliano MW and Salemme FR (1992) Crystallographic and thermodynamic comparison of natural and synthetic ligands bound to streptavidin. Journal of the American Chemical Society 114: 3197–3200.

Wendt KS, Schall I, Huber R, Buckel W and Jacob U (2003) Crystal structure of the carboxyltransferase subunit of the bacterial sodium ion pump glutaconyl‐coenzyme A decarboxylase. The EMBO Journal 22: 3493–3502.

Wilchek M and Bayer EA (eds) (1990) Avidin–biotin technology. Methods in Enzymology, vol. 184. San Diego, CA: Academic Press.

Wilson KP, Shewchuk LM, Brennan RG, Otsuka AJ and Matthews BW (1992) Escherichia coli biotin holoenzyme synthetase/bio repressor crystal structure delineates the biotin‐ and DNA‐binding domains. Proceedings of the National Academy of Sciences of the USA 89: 9257–9261.

Zhang H, Yang Z, Shen Y and Tong L (2003) Crystal structure of the carboxyltransferase domain of acetyl‐coenzyme A carboxylase. Science 299: 2064–2067.

Further Reading

Artymiuk PJ, Poirrette AR, Rice DW and Willett P (1996) Biotin carboxylase comes into the fold. Nature Structural Biology 3: 128–132.

Attwood PV (1995) The structure and the mechanism of action of pyruvate carboxylase. International Journal of Biochemistry and Cell Biology 27: 231–249.

Galperin MY and Koonin EV (1997) A diverse superfamily of enzymes with ATP‐dependent carboxylate‐amine/thiol ligase activity. Protein Science 6: 2639–2643.

Jitrapakdee S and Wallace JC (1999) Structure, function and regulation of pyruvate carboxylase. Biochemical Journal 340: 1–16.

Knowles JR (1989) The mechanism of biotin‐dependent enzymes. Annual Review of Biochemistry 58: 195–221.

Lindqvist Y and Schneider G (1996) Protein–biotin interactions. Current Opinion in Structural Biology 6: 798–803.

Moss J and Lane MD (1971) The biotin‐dependent enzymes. Advances in Enzymology and Related Areas of Molecular Biology 35: 321–442.

Samols D, Thornton CG, Murtif VL, et al. (1988) Evolutionary conservation among biotin enzymes. Journal of Biological Chemistry 263: 6461–6464.

Toh H, Kondo H and Tanabe T (1993) Molecular evolution of biotin‐dependent carboxylases. European Journal of Biochemistry 215: 687–696.

Wood HG and Barden RE (1977) Biotin enzymes. Annual Review of Biochemistry 46: 385–413.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Waldrop, Grover L(Jan 2015) Biotin. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0000644.pub2]