Biotinidase

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Biotinidase
Properties of human protein
Mass / length primary structure 523 AA (human)
Isoforms 4th
Identifier
Gene name BTD
External IDs
Enzyme classification
EC, category 3.5.1.12 ,  hydrolase
Response type hydrolysis
Substrate Biocytin + H 2 O
Products Biotin + lysine
Occurrence
Homology family BTD / VNN
Parent taxon Opisthokonta

Biotinidase is an enzyme from the hydrolase class that releases the vitamin biotin from proteins . This is important for the recycling of biotin that takes place in the body, but also for its absorption from food.

After research into the occurrence and distribution of biotinidase in the various organisms in the 1950s and 1960s, the enzyme returned to scientific interest in 1983 when the discovery that a biotinidase defect is the cause of a rare, hereditary metabolic disease . Exploring the various manifestations of the now as biotinidase defect designated (Engl.  Biotinidase deficiency ) brought a number of new information about the function of biotinidase and the role of biotin in the body.

Occurrence

So far, biotinidase has been found in various vertebrates , fruit flies and fungi , in addition to humans . Although the biotinidases of the different species differ, certain sections of the enzyme have been preserved in the course of evolution . The family tree of biotinidase extends into the Precambrian .

Some bacteria, such as the lactic acid bacteria Lactobacillus casei or Enterococcus faecalis (formerly Streptococcus faecalis ) also contain an enzyme that can release biotin, but another lactic acid bacterium Lactobacillus arabinosus does not.

structure

The complete sequence of amino acids in protein is known for some biotinidases from different living organisms . Human biotinidase has 523 amino acids, that of the rat 521, the mouse 520 and the puffer fish 504 amino acids. In other animals, fragments could only be sequenced.

Little is known about the three-dimensional structure. A crystal structure analysis has so far failed due to the difficulty of crystallizing biotinidase (as of early 2009). There is only one model based on computer simulations, but according to the authors it is uncertain in detail.

function

The biotinidase catalytically splits the biocytin produced during the breakdown of the carboxylases into biotin and the amino acid lysine .

Biocytin + H 2 O + Biotin L-lysine

There is also evidence that biotinidase also plays a role as a transferase . According to experiments in vitro , the enzyme is able to chemically bind split-off biotin. If histones are present that have binding sites for biotin, they are biotinylated. Biotinidase is not the only enzyme that can bind biotin to histones; holocarboxylase synthetase also has this ability. However, biotinidase is also able to debiotinylate histones. Which of the reactions take place on which histones under which conditions is the subject of current research. Epigenetic effects are discussed.

genetics

The gene coding for biotinidase is located in humans on chromosome 3 in the p25 region. A number of mutations are known to lead to a metabolic disease called multiple carboxylase deficiency . In the meantime, tests for biotinidase deficiency are carried out in many countries as part of newborn screening .

supporting documents

  1. ^ J. Hymes, B. Wolf: Biotinidase and its roles in biotin metabolism. In: Clin. Chim. Acta 255 (1); 1996 Nov 15: pp. 1-11. PMID 8930409
  2. ↑ a b Uniprot protein database , entries for biotinidase
  3. ↑ B. Wolf, K. Jensen: Evolutionary conservation of biotinidase: implications for the enzyme's structure and subcellular localization. In: Mol. Genet. Metab. 86 (1-2); Sep / Oct 2005: pp. 44-50. PMID 16150625
  4. ↑ Family tree of the gene family in HOGENOM
  5. ↑ M. Koivusalo, C. Elorriaga, Y. Kaziro, S. Ochoa: Bacterial Biotinidase. In: J. Biol. Chem. 238; March 1963: pp. 1038-42. PMID 14034272 (full text)
  6. ↑ K. Hayakawa, L. Guo, EATerentyeva, KX Li, H. Kimura, M. Hirano, K. Yoshikawa, T. Nagamine, N. Katsumata, T. Ogata, T. Tanaka: Determination of specific activities and kinetic constants of biotinidase and lipoamidase in LEW rat and Lactobacillus casei (Shirota). In: J. Chromatogr. B analyte. Technol. Biomed. Life Sci. 844 (2); Dec 2006: pp. 240-50. Epub July 2006. PMID 16876490
  7. ↑ Protein database UniProt P43251
  8. ↑ K. Pindolia, K. Jensen, B. Wolf: Three dimensional structure of human biotinidase: computer modeling and functional correlations. In: Mol. Genet. Metab. 92 (1-2); Sep / Oct 2007, pp. 13-22. Epub July 12, 2007. PMID 17629531
  9. ↑ J. Hymes, B. Wolf: Human Biotinidase Isn't Just for Recycling Biotin. In: J. Nutr. 129; Feb 1999: S. 485S – 489S PMID 10064314 (full text)
  10. ↑ YI Hassan, J. Zempleni: Epigenetic regulation of chromatin structure and gene function by biotin. In: J. Nutr. 136 (7); 2006 Jul: pp. 1763–5 PMID 16772434 (full text)
  11. ↑ Database entry on biotinidase.  In: Online Mendelian Inheritance in Man . (English)