2732
T3D2690
Biotin
Biotin is an enzyme co-factor present in minute amounts in every living cell. Biotin is also known as vitamin H or B7 or coenzyme R. It occurs mainly bound to proteins or polypeptides and is abundant in liver, kidney, pancreas, yeast, and milk. Biotin has been recognized as an essential nutrient. Our biotin requirement is fulfilled in part through diet, through endogenous reutilization of biotin and perhaps through capture of biotin generated in the intestinal flora. The utilization of biotin for covalent attachment to carboxylases and its reutilization through the release of carboxylase biotin after proteolytic degradation constitutes the 'biotin cycle'. Biotin deficiency is associated with neurological manifestations, skin rash, hair loss and metabolic disturbances that are thought to relate to the various carboxylase deficiencies (metabolic ketoacidosis with lactic acidosis). It has also been suggested that biotin deficiency is associated with protein malnutrition, and that marginal biotin deficiency in pregnant women may be teratogenic. Biotin acts as a carboxyl carrier in carboxylation reactions. There are four biotin-dependent carboxylases in mammals: those of propionyl-CoA (PCC), 3-methylcrotonyl-CoA (MCC), pyruvate (PC) and acetyl-CoA carboxylases (isoforms ACC-1 and ACC-2). All but ACC-2 are mitochondrial enzymes. The biotin moiety is covalently bound to the epsilon amino group of a Lysine residue in each of these carboxylases in a domain 60-80 amino acids long. The domain is structurally similar among carboxylases from bacteria to mammals. There are four biotin-dependent carboxylases in mammals: those of propionyl-CoA (PCC), 3-methylcrotonyl-CoA (MCC), pyruvate (PC) and acetyl-CoA carboxylases (isoforms ACC-1 and ACC-2). All but ACC-2 are mitochondrial enzymes. The biotin moiety is covalently bound to the epsilon amino group of a Lys residue in each of these carboxylases in a domain 60-80 amino acids long. The domain is structurally similar among carboxylases from bacteria to mammals. Evidence is emerging that biotin participates in processes other than classical carboxylation reactions. Specifically, novel roles for biotin in cell signaling, gene expression, and chromatin structure have been identified in recent years. Human cells accumulate biotin by using both the sodium-dependent multivitamin transporter and monocarboxylate transporter 1. These transporters and other biotin-binding proteins partition biotin to compartments involved in biotin signaling: cytoplasm, mitochondria, and nuclei. The activity of cell signals such as biotinyl-AMP, Sp1 and Sp3, nuclear factor (NF)-kappaB, and receptor tyrosine kinases depends on biotin supply. Consistent with a role for biotin and its catabolites in modulating these cell signals, greater than 2000 biotin-dependent genes have been identified in various human tissues. Many biotin-dependent gene products play roles in signal transduction and localize to the cell nucleus, consistent with a role for biotin in cell signaling. Posttranscriptional events related to ribosomal activity and protein folding may further contribute to effects of biotin on gene expression. Finally, research has shown that biotinidase and holocarboxylase synthetase mediate covalent binding of biotin to histones (DNA-binding proteins), affecting chromatin structure; at least seven biotinylation sites have been identified in human histones. Biotinylation of histones appears to play a role in cell proliferation, gene silencing, and the cellular response to DNA repair. Roles for biotin in cell signaling and chromatin structure are consistent with the notion that biotin has a unique significance in cell biology. (A7825, A7826).
58-85-5
171548
C10H16N2O3S
243.080340
White powder.
232 dec°C
220 mg/L (at 25°C)
Oral.
Systemic - approximately 50%
Biotin is necessary for the proper functioning of enzymes that transport carboxyl units and fix carbon dioxide, and is required for various metabolic functions, including gluconeogenesis, lipogenesis, fatty acid biosynthesis, propionate metabolism, and catabolism of branched-chain amino acids.
No indication of carcinogenicity to humans (not listed by IARC).
For nutritional supplementation, also for treating dietary shortage or imbalance.
Prolonged skin contact may cause irritation.
2009-07-21T20:26:07Z
2014-12-24T20:25:49Z
Biotin
C00120
104620
107970
135630
138320
142705
152445
164840
180640
186790
188370
188411
189918
189919
189920
200350
210200
210210
232000
232050
245400
253260
253270
266150
271930
275550
603032
604024
606054
606152
606557
606558
607483
608786
609010
609014
609018
609019
609751
610509
15956
BIOTIN
Biotin
DB00121
BTN
2312
true
[H][C@@]1(CCCCC(O)=O)SC[C@]2([H])N=C(O)N[C@]12[H]
C10H16N2O3S
InChI=1S/C10H16N2O3S/c13-8(14)4-2-1-3-7-9-6(5-16-7)11-10(15)12-9/h6-7,9H,1-5H2,(H,13,14)(H2,11,12,15)/t6-,7-,9-/m0/s1
InChIKey=YBJHBAHKTGYVGT-ZKWXMUAHSA-N
244.311
244.088163078
Endogenous
Solid
0.5
HMDB00030
CHEMBL857
149962
<p>Takayoshi Mitsunaga, Kiyoto Chinushi, Tadashi Umezu, “Water-soluble biotin-containing preparation.” U.S. Patent US4277488, issued May, 1940.</p>