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EC 4.3.1.3 Details

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EC number

4.3.1.3

Accepted name

histidine ammonia-lyase

Reaction

L-histidine = urocanate + NH₃

Other name(s)

histidase, histidinase, histidine α-deaminase, L-histidine ammonia-lyase

Systematic name

L-histidine ammonia-lyase (urocanate-forming)

CAS registry number

9013-75-6

Comment

This enzyme is a member of the aromatic amino acid lyase family, other members of which are EC 4.3.1.23 (tyrosine ammonia-lyase), EC 4.3.1.24 (phenylalanine ammonia-lyase) and EC 4.3.1.25 (phenylalanine/tyrosine ammonia-lyase). The enzyme contains the cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO), which is common to this family [4]. This unique cofactor is formed autocatalytically by cyclization and dehydration of the three amino-acid residues alanine, serine and glycine [5]. This enzyme catalyses the first step in the degradation of histidine and the product, urocanic acid, is further metabolized to glutamate [2,3].

History

created 1961, modified 2008

EC Tree

4.1 Carbon-carbon lyases

4.2 Carbon-oxygen lyases

4.3 Carbon-nitrogen lyases

4.3.1 Ammonia-lyases

4.3.1.1 aspartate ammonia-lyase

4.3.1.2 methylaspartate ammonia-lyase

4.3.1.3 histidine ammonia-lyase

4.3.1.4 formimidoyltetrahydrofolate cyclodeaminase

4.3.1.5 phenylalanine ammonia-lyase

4.3.1.6 β-alanyl-CoA ammonia-lyase

4.3.1.7 ethanolamine ammonia-lyase

4.3.1.8 created 1972, modified 1982, modified 1989, deleted 2003

4.3.1.9 glucosaminate ammonia-lyase

4.3.1.10 serine-sulfate ammonia-lyase

4.3.1.11 dihydroxyphenylalanine ammonia-lyase

4.3.1.12 ornithine cyclodeaminase

4.3.1.13 carbamoyl-serine ammonia-lyase

4.3.1.14 3-aminobutyryl-CoA ammonia-lyase

4.3.1.15 diaminopropionate ammonia-lyase

4.3.1.16 threo-3-hydroxy-L-aspartate ammonia-lyase

4.3.1.17 L-serine ammonia-lyase

4.3.1.18 D-serine ammonia-lyase

4.3.1.19 threonine ammonia-lyase

4.3.1.20 erythro-3-hydroxy-L-aspartate ammonia-lyase

4.3.1.21 created 1965 as EC 4.2.1.26, transferred 2002 to EC 4.3.1.21, deleted 2004

4.3.1.22 3,4-dihydroxyphenylalanine reductive deaminase

4.3.1.23 tyrosine ammonia-lyase

4.3.1.24 phenylalanine ammonia-lyase

4.3.1.25 phenylalanine/tyrosine ammonia-lyase

4.3.1.26 chromopyrrolate synthase

4.3.1.27 threo-3-hydroxy-D-aspartate ammonia-lyase

4.3.1.28 L-lysine cyclodeaminase

4.3.1.29 D-glucosaminate-6-phosphate ammonia-lyase

4.3.1.30 dTDP-4-amino-4,6-dideoxy-D-glucose ammonia-lyase

4.3.1.31 L-tryptophan ammonia lyase

4.3.1.32 7,8-didemethyl-8-hydroxy-5-deazariboflavin synthase

4.3.2 Amidine-lyases

4.3.3 Amine-lyases

4.3.99 Other carbon-nitrogen lyases

4.4 Carbon-sulfur lyases

4.5 Carbon-halide lyases

4.6 Phosphorus-oxygen lyases

4.7 carbon-phosphorus lyases

4.7.1 carbon-phosphorus lyases (only sub-subclass identified to date)

4.8 Nitrogen-oxygen lyases

4.98 ATP-independent chelatases