Most enzymes that catalyse this reaction are pyridoxal-phosphate-dependent, although some enzymes contain an iron-sulfur cluster instead . The reaction catalysed by both types of enzymes involves the initial elimination of water to form an enamine intermediate (hence the enzyme's original classification as EC 4.2.1.13, L-serine dehydratase), followed by tautomerization to an imine form and hydrolysis of the C-N bond. The latter reaction, which can occur spontaneously, is also be catalysed by EC 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase. This reaction is also carried out by EC 4.3.1.19, threonine ammonia-lyase, from a number of sources.
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SYSTEMATIC NAME
IUBMB Comments
L-serine ammonia-lyase (pyruvate-forming)
Most enzymes that catalyse this reaction are pyridoxal-phosphate-dependent, although some enzymes contain an iron-sulfur cluster instead [6]. The reaction catalysed by both types of enzymes involves the initial elimination of water to form an enamine intermediate (hence the enzyme's original classification as EC 4.2.1.13, L-serine dehydratase), followed by tautomerization to an imine form and hydrolysis of the C-N bond. The latter reaction, which can occur spontaneously, is also be catalysed by EC 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase. This reaction is also carried out by EC 4.3.1.19, threonine ammonia-lyase, from a number of sources.
7.7 mol iron per mol dimer, two (4Fe-4S)2+ clusters per dimer in anaerobically isolated enzyme, exposure to air results in loss of clusters and concomitant loss of enzyme activity
the enzyme is inactive in crude extract and can be activated with iron and dithiothreitol. The activation requires oxygen, and is inhibited by free radical scavengers and by diethylenentriamine pentaacetic acid, which prevents Fe cycling
Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes L-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant lacking 4Fe4S L-serine deaminases SdaA, SdaB, and TdcG is unable to do this. The high level of L-serine that accumulates when the mutant is exposed to amino acid mixtures starves the cells for C1 units and interferes with cell wall synthesis. Growth in minimal medium containing glucose, ammonium sulfate, and Casamino Acids results in deformed cells and frequently lysing, which can be reversed by adding S-adenosylmethionine
Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes L-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant lacking 4Fe4S L-serine deaminases SdaA, SdaB, and TdcG is unable to do this. The high level of L-serine that accumulates when the mutant is exposed to amino acid mixtures starves the cells for C1 units and interferes with cell wall synthesis. Growth in minimal medium containing glucose, ammonium sulfate, and Casamino Acids results in deformed cells and frequently lysing, which can be reversed by adding S-adenosylmethionine