IUBMB Enzyme Nomenclature


Accepted name: β-(isoxazolin-5-on-2-yl)-L-alanine synthase

Reaction: O-acetyl-L-serine + isoxazolin-5-one = 3-(5-oxoisoxazolin-2-yl)-L-alanine + acetate

For diagram of reaction click here.

Other name(s): O3-acetyl-L-serine:isoxazolin-5-one 2-(2-amino-2-carboxyethyl)transferase

Systematic name: O-acetyl-L-serine:isoxazolin-5-one 2-(2-amino-2-carboxyethyl)transferase

Comments: The enzyme from the plants Lathyrus odoratus (sweet pea) and L. sativus (grass pea) also forms 3-(5-oxoisoxazolin-4-yl)-L-alanine in vitro (cf. EC However, only 3-(5-oxoisoxazolin-2-yl)-L-alanine is formed in vivo. 3-(5-oxoisoxazolin-2-yl)-L-alanine is the biosynthetic precursor of the neurotoxin N3-oxalyl-L-2,3-diaminopropanoic acid, the cause of lathyrism. Closely related and possibly identical to EC, cysteine synthase, and EC, β-pyrazolylalanine synthase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Ikegami, F., Kamiya, M., Kuo, Y.H., Lambein, F. and Murakoshi, I. Enzymatic synthesis of two isoxazolylalanine isomers by cysteine synthases in Lathyrus species. Biol. Pharm. Bull. 19 (1996) 1214-1215. [PMID: 8889043]

[EC created 2014]

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