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Biotin
Other names	Vitamin B7; Vitamin H
Properties
Molecular formula	C10H16N2O3S
Molar mass	244.31 g/mol
Solubility in water	Soluble
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Vitamin H redirects here. In medical slang, Vitamin H may also refer to haloperidol. In gamer slang Vitamin H may also refer to the Halo (series)

Biotin, also known as vitamin H or B₇, has the chemical formula C₁₀H₁₆N₂O₃S (Biotin; Coenzyme R, Biopeiderm), is a water-soluble B-complex vitamin which is composed of an ureido (tetrahydroimidizalone) ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring. Biotin is a cofactor in the metabolism of fatty acids and leucine, and in gluconeogenesis. Image File history File links Question_book-3. ... Image File history File links No higher resolution available. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... The plimsoll symbol as used in shipping In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals exactly). ... Haloperidol (sold under the tradenames Aloperidin, Bioperidolo, Brotopon, Dozic, Duraperidol (Germany), Einalon S, Eukystol, Haldol, Halosten, Keselan, Linton, Peluces, Serenace, Serenase, Sigaperidol) is a conventional, or typical, butyrophenone antipsychotic drug. ... It has been suggested that Covenant Vehicles in Halo be merged into this article or section. ... Retinol (one vitamer of Vitamin A) A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. ... Tetrahydrothiophene is a heterocyclic organic compound consisting of a five-membered ring containing four carbon atoms and a sulfur atom. ... Valeric acid, or pentanoic acid, is a straight chain alkyl carboxylic acid with the chemical formula CH3(CH2)3COOH. Like other low molecular weight carboxylic acids, it has a very unpleasant odor. ... A cofactor is the following: In mathematics a cofactor is the minor of an element of a square matrix. ... Not to be confused with fats. ... Leucine is one of the 20 most common amino acids and coded for by DNA. It is isomeric with isoleucine. ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ...

General overview

Biotin is necessary for cell growth, the production of fatty acids, and the metabolism of fats and amino acids. It plays a role in the Citric acid cycle, which is the process by which biochemical energy is generated during aerobic respiration. Biotin not only assists in various metabolic reactions, but also helps to transfer carbon dioxide. Biotin is also helpful in maintaining a steady blood sugar level. Biotin is often recommended for strengthening hair and nails. Consequently, it is found in many cosmetic and health products for the hair and skin. Overview of the citric acid cycle The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle, after Hans Adolf Krebs who identified the cycle) is a series of chemical reactions of central importance in all living cells that use oxygen as part... Cellular respiration was discovered by mad scientist Mr. ...

Deficiency is extremely rare, as intestinal bacteria generally produce an excess of the body's daily requirement. For that reason, statutory agencies in many countries (e.g., the Australian Department of Health and Aging) do not prescribe a recommended daily intake.

Sources

Dietary

Biotin is widely distributed in a variety of foods, but most often at low concentrations. There are only a couple of foods which contain biotin in large amounts, including royal jelly and brewer's yeast. The most important natural sources of biotin in human nutrition are milk, liver, egg (egg yolk), and some vegetables. The most important natural sources in feeding nonruminant animals are oilseed meals, alfalfa, and dried yeasts. It is important to note that the biotin content of food varies and can be influenced by factors such as plant variety, season, and yield (endopserm-to-pericarp ratio).^[1]

• Adequate intake are determined for nutrients when there is insufficient scientific evidence to establish a Recommended Dietary Allowance (RDA). These values are set as goals for individuals to support adequate nutritional status. There is no current Tolerable Upper Limit (UL) set for biotin as research has indicated that high levels of intake by humans has no detrimental effects.^[2]

Bioavailability

Studies on the bioavailability of biotin have have been conducted in rats and in chicks. From these studies, it was concluded that biotin bioavailability may be low or variable depending on the type of food being consumed, but in general, approximately half of the biotin in most foods is considered to be biologically available. The biotin present in corn is readily available, however most grain have about a 20-40% bioavailability of biotin ^[3].

A possible explanation for the wide variability in biotin bioavailabilty is due to ability of an organism to break various biotin-protein bonds from food. Whether an organism has an enzyme with the ability to break that bond will determine the bioavailability of biotin from the foodstuff ^[4].

Factors that Affect Biotin Requirements

The frequency of marginal biotin status is not known, but the incidence of low circulating biotin levels in alcoholics has been found to be much greater than in the general population. Also, relatively low levels of biotin have been reported in the urine or plasma of patients who have had partial gastrectomy or who have other causes of achlorhydria, burn patients, epileptics, elderly individuals, and athletes.^[5] Pregnancy and lactation may be associated with an increased demand for biotin. In pregnancy, this may be due to a possible acceleration of biotin catabolism, whereas in lactation, the higher demand has yet to be elucidated. Recent studies have shown that marginal biotin deficiency can be present in human gestation, as evidenced by increased urinary excretion of 3-hydroxyisovaleric acid, decreased urinary excretion of biotin and bisnorbiotin, and decreased plasma concentration of biotin. Additionally, smoking may further accelerate biotin catabolism in women.^[6]

Uses

Hair Problems

Biotin supplements are often recommended as a natural product to counteract the problem of hair loss in both children and adults. There are, however, no studies that show any benefit in any case where the subject is not actually biotin deficient. The signs and symptoms of biotin deficiency include hair loss which progresses in severity to include loss of eye lashes and eye brows in severely deficient subjects. Some shampoos are available that contain biotin, but it is doubtful whether they would have any useful effect, as biotin is not absorbed well through the skin.

Cradle cap (seborrheic dermatitis)

Children with a rare inherited metabolic disorder called phenylketonuria (PKU; in which one is unable to break down the amino acid phenylalanine) often develop skin conditions such as eczema and seborrheic dermatitis in areas of the body other than the scalp. The scaly skin changes that occur in people with PKU may be related to poor ability to use biotin. Increasing dietary biotin has been known to improve seborrheic dermatitis^{[citation needed]} in these cases. Phenylketonuria (PKU) is an autosomal recessive genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH). ... For the beetle, see Exema. ... Seborrhoeic dermatitis is a skin disorder affecting the scalp, face and trunk causing scaly, flaky, itchy, red skin. ... Seborrhoeic dermatitis is a skin disorder affecting the scalp, face and trunk causing scaly, flaky, itchy, red skin. ...

Diabetes

People with type 2 diabetes often have low levels of biotin. Biotin may be involved in the synthesis and release of insulin. Preliminary studies in both animals and people suggest that biotin may help improve blood glucose control in those with diabetes, particularly type 2 diabetes.^[7] Specifically, biotin doses in excess of nutritional requirements lower postprandial glucose and improve glucose tolerance.^[8] This article is about the disease that features high blood sugar. ...

Deficiency

Biotin deficiency is relatively rare and mild, and can be addressed with supplementation. Such deficiency can be caused by the excessive consumption of raw egg whites, which contain high levels of the protein avidin, which binds biotin strongly. Avidin is inactivated by cooking, while the biotin remains intact. Biotin deficiency can have a very serious, even fatal, outcome if it is allowed to progress without treatment. ... Albumen redirects here. ... Avidin is a protein found in egg white that binds with biotin, found in egg yolk. ...

Biotinidase deficiency is not due to inadequate biotin, but rather to a deficiency in the enzymes which process it. Biotin, also known as vitamin H or B7 and C10H16N2O3S (Biotin; Coenzyme R, Biopeiderm), is a water-soluble B-complex vitamin which is composed of an ureido ring fused with a tetrahydrothiophene ring. ...

Signs of Biotin Deficiency: In general, appetite and growth are decreased. Dermatologic symptoms include dermatitis, alopecia, and achromitrochia. Perosis (a shortening and thickening of bones) is seen in the skeleton. FLKS (fatty liver and kidney syndrom) and hepatic steatosis also can occur.^[9]

Toxicity

Animal studies have indicated few, if any, affects due to toxic doses of biotin. This may provide evidence that both animals and humans may tolerate doses of at least an order of magnitude greater than each of their nutritional requirements. There are no reported cases of adverse effects from receiving high doses of the vitamin, particularly when used in the treatment of metabolic disorders causing sebhorrheic dermatitis in infants.^[10]

Biochemistry

Biotin is a cofactor responsible for carbon dioxide transfer in several carboxylase enzymes: A cofactor is any substance that needs to be present in addition to an enzyme to catalyze a certain reaction. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Carboxylation in chemistry is a chemical reaction in which a carboxylic acid group is introduced in a substrate. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ...

• Acetyl-CoA carboxylase alpha
• Acetyl-CoA carboxylase beta
• Methylcrotonyl-CoA carboxylase
• Propionyl-CoA carboxylase
• Pyruvate carboxylase

The attachment of biotin to various chemical sites, called biotinylation, can be used as an important laboratory technique to study various processes including protein localization, protein interactions, DNA transcription and replication. Biotin itself is known to biotinylate histones^{[citation needed]}, but is not found naturally in chromatin. Holocarboxylase synthetase is involved in the binding of biotin. Acetyl-CoA carboxylase (ACC) is a biotin-dependent enzyme that catalyses carboxylation of acetyl CoA to produce malonyl CoA through its two catalytic activities, biotin carboxylase (BC) and carboxyltransferase (CT). ... Acetyl-CoA carboxylase (ACC) is a biotin-dependent enzyme that catalyses carboxylation of acetyl CoA to produce malonyl CoA through its two catalytic activities, biotin carboxylase (BC) and carboxyltransferase (CT). ... Methylcrotonyl CoA carboxylase (MCC) or 3-Methylcrotonyl CoA carboxylase is a biotin-requiring enzyme located in the mitochondria. ... Propionyl-CoA carboxylase catalyses the carboxylation reaction of propionyl CoA. The product of the reaction is D-methylmalonyl CoA. ATP + propanoyl-CoA + HCO3- <=> ADP + phosphate + (S)-methylmalonyl-CoA Category: ... Pyruvate carboxylase is an enzyme of the ligase class that catalyzes the reversible carboxylation of pyruvate to form oxaloacetate. ... In biochemistry, biotinylation is the process of covalently attaching a biotin tag to a molecule or surface. ... Protein-protein interactions refer to the association of protein molecules and the study of these associations from the perspective of biochemistry, signal transduction and networks. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... DNA replication. ... HLCS (holocarboxylase synthetase (biotin-(proprionyl-Coenzyme A-carboxylase (ATP-hydrolysing)) ligase)) is a human gene that provides instructions for making an enzyme called holocarboxylase synthetase (EC 6. ...

Biotin binds very tightly to the tetrameric protein avidin (also streptavidin and neutravidin), with a dissociation constant K_d in the order of 10^-15 mol/L (Bonjour, 1977; Green 1975; and Roth, 1985). This is often used in different biotechnological applications. Until 2005, very harsh conditions were required to break the biotin-streptavidin bond.^[11] Avidin is a protein found in egg white that binds with biotin, found in egg yolk. ... Streptavidin (less commonly spelled streptavidine) is a tetrameric protein purified from Streptomyces avidinii that binds very tightly to the vitamin biotin with a dissociation constant (Kd) of ~ 10^(–15) M. This is one of the strongest biochemical interactions known, and is widely taken advantage of in scientific laboratories. ... In chemistry and biochemistry, a dissociation constant or an ionization constant is a specific type of equilibrium constant used for reversible reactions or processes. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Laboratory uses

In the biology laboratory, biotin is often chemically linked, or tagged, to a molecule or protein for biochemical assays. This process is called biotinylation. Since avidins bind preferentially to biotin, biotin-tagged molecules can be extracted from a sample by mixing them with beads with covalently-attached avidin, and washing away anything unbound to the beads. In biochemistry, biotinylation is the process of covalently attaching a biotin tag to a molecule or surface. ...

For example, biotin can be attached to a molecule of interest (e.g. a protein), and this modified molecule will be mixed with a complex mixture of proteins. Avidin or streptavidin beads are added to the mixture, and the biotinylated molecule will bind to the beads. Any other proteins binding to the biotinylated molecule will also stay with the beads. All other unbound proteins can be washed away, and the scientist can use a variety of methods to determine which proteins have bound to the biotinylated molecule.

Biotinylated antibodies are used to capture avidin or streptavidin in both the ELISPOT and ELISA techniques. The Enzyme-linked immunosorbent spot (ELISPOT) is a common method for monitoring immune responses in humans and animals. ... Elisa (born Elisa Toffoli on 19 December 1977) is an Italian singer and solo artist, writing and performing within several genres, notably rock, blues, soul and ambient. ...

Ruminant Nutrition

Ruminal bacteria normally synthesize biotin. Biotin is not extensively metabolized in the rumen and increased intake of dietary biotin resultes in elevated concentrations of biotin in serum and milk.^[12] Unpublished epidemiologic data suggest a negative relationship between serum concentrations of biotin and the incidence of clinical lameness in dairy cattle. Feeding approximately 20 mg/day of supplemental biotin statistically improved measures of hoof health. Currently, insufficient data are available at this time to quantify the requirement for biotin of dairy cattle.

References

1. ^ Combs,G. F. Jr. The Vitamins: Fundamental Aspects in Nutrition and Health. 3rd Edition. Ithaca, NY: Elsevier Academic Press; 2008; pg.332
2. ^ McGuire M, Beerman KA. Nutritional sciences: from fundamentals to food. California: Thomson Wadsworth, 2007.
3. ^ Combs, G.F. The Vitamins: Fundamental Aspects in Nutrition and Health. 2008. San Diego: Elsevier, Inc.
4. ^ Combs, G.F. The Vitamins: Fundamental Aspects in Nutrition and Health. 2008. San Diego: Elsevier, Inc.
5. ^ Combs, Gerald. The Vitamins: Fundamental Aspects in Nutrition and Health, Third Edition. Burlington: Elsevier Academic Press, 2008.
6. ^ Bowman, BA and Russell, RM. (eds) Biotin: In Present Knowledge in Nutrition, Ninth Edition, Vol 1. Washington, DC: Internation Life Sciences Institute, 2006.
7. ^ Campbell, R. Keith (Nov 2006). "A Critical Review of Chromium Picolinate and Biotin". U.S. Pharmacist 31 (11). 
8. ^ Combs, Gerald. The Vitamins: Fundamental Aspects in Nutrition and Health. Burlington: Elsevier Academic Press, 2008.
9. ^ Combs, Gerald. The Vitamins: Fundamental Aspects in Nutrition and Health. Burlington: Elsevier Academic Press, 2008.
10. ^ Combs,G. F. Jr. The Vitamins: Fundamental Aspects in Nutrition and Health. 2nd Edition. Ithaca, NY: Elsevier Academic Press; 1998; pg.360
11. ^ Holmberg A, Blomstergren A, Nord O et al. (2005). "The biotin-streptavidin interaction can be reversibly broken using water at elevated temperatures". Electrophoresis 26 (3): 501-10. doi:10.1002/elps.200410070. PMID 15690449. 
12. ^ Template:National Research Council. 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Sci., Washington, DC.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

See also

• Biotinylation
• Avidin
• Streptavidin
• NeutrAvidin

In biochemistry, biotinylation is the process of covalently attaching a biotin tag to a molecule or surface. ... Avidin is a protein found in egg white that binds with biotin, found in egg yolk. ... Streptavidin (less commonly spelled streptavidine) is a tetrameric protein purified from Streptomyces avidinii that binds very tightly to the vitamin biotin with a dissociation constant (Kd) of ~ 10^(–15) M. This is one of the strongest biochemical interactions known, and is widely taken advantage of in scientific laboratories. ...

External links

• Jane Higdon, "Biotin", Micronutrient Information Center, Linus Pauling Institute
• Biotin - Biocytin (Brewer's YeastBiotin Complex)
• Clercq, Pierre J. De (1997). "Biotin: A Timeless Challenge for Total Synthesis". Chemical Review 97: 1755-1792. doi:10.1021/cr950073e.