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.
