Aspartokinase


Aspartokinase

Aspartokinase (or Aspartate kinase) is an enzyme that catalyzes the phosphorylation of the amino acid aspartate. This reaction is the first step in the biosynthesis of three essential amino acids: methionine, lysine, and Threonine, known as the "aspartate family". The gene for aspartkinase is present only in microorganisms and plants; it is not present in animals, who must obtain aspartate-family amino acids in their diet.

In E. coli, aspartokinase is present as three independently regulated isozymes, each of which is specific to one of the three downstream biochemical pathways. This allows the independent regulation of the rates of methionine, lysine, and threonine production. The forms that produce threonine and lysine are subject to feedback inhibition and all three can be repressed at the level of gene expression by high concentrations of their end products. [cite journal|author=Voet D, Voet JG.
year= 2004|title=Biochemistry 3rd ed. Wiley: Hoboken, NJ.|volume=1|pmid=16729065|doi=10.1038/msb4100040|journal=Molecular Systems Biology|pages=E1
] . Absence from animals makes these enzymes key targets for new herbicides and biocides and for improvements in nutritional value of crops. [cite journal|author=Viola RE.|journal=Acc Chem Res.|year= 2001|vol=34|title=The central enzymes of the aspartate family of amino acid biosynthesis|pmid=11352712|pages=339–49|doi=10.1021/ar000057q|volume=34]

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Look at other dictionaries:

  • aspartokinase — Enzyme that phosphorylates L aspartate to produce aspartyl phosphate …   Dictionary of molecular biology

  • aspartokinase — as·par·to·kin·ase (ə spär tō kīʹnās) n. An enzyme that catalyzes aspartic acid phosphorylation by ATP.   [aspartic acid + kinase.] * * * …   Universalium

  • aspartokinase — noun An enzyme that catalyzes the phosphorylation of the amino acid aspartate, the first step in the biosynthesis of three essential amino acids: methionine, lysine, and threonine …   Wiktionary

  • aspartokinase — as·par·to·ki·nase ə .spärt ō kī .nās, .nāz n an enzyme that catalyzes the phosphorylation of aspartic acid by ATP …   Medical dictionary

  • aspartokinase — as·par·to·kinase …   English syllables

  • aspartokinase — əˌspärd.ōˌ noun Etymology: aspartic acid + o + kinase : an enzyme that catalyzes the phosphorylation of aspartic acid by ATP …   Useful english dictionary

  • metabolism — /meuh tab euh liz euhm/, n. 1. Biol., Physiol. the sum of the physical and chemical processes in an organism by which its material substance is produced, maintained, and destroyed, and by which energy is made available. Cf. anabolism, catabolism …   Universalium

  • Lysine — Lysine …   Wikipedia

  • Protein — Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by …   Wikipedia

  • Methionine — Methionine …   Wikipedia


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