IUBMB Enzyme Nomenclature


Accepted name: N-succinylornithine carbamoyltransferase

Reaction: carbamoyl phosphate + N2-succinyl-L-ornithine = phosphate + N-succinyl-L-citrulline

Glossary: N-acetyl-L-citrulline = N5-acetylcarbamoyl-L-ornithine

Other name(s): succinylornithine transcarbamylase; N-succinyl-L-ornithine transcarbamylase; SOTCase

Systematic name: carbamoyl phosphate:N2-succinyl-L-ornithine carbamoyltransferase

Comments: This enzyme is specific for N-succinyl-L-ornithine and cannot use either L-ornithine (see EC, ornithine carbamoyltransferase) or N-acetyl-L-ornithine (see EC, N-acetylornithine carbamoyltransferase) as substrate. However, a single amino-acid substitution (Pro90 → Glu90) is sufficient to switch the enzyme to one that uses N-acetyl-L-ornithine as substrate. It is essential for de novo arginine biosynthesis in the obligate anaerobe Bacteroides fragilis, suggesting that this organism uses an alternative pathway for synthesizing arginine.

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


1. Shi, D., Morizono, H., Cabrera-Luque, J., Yu, X., Roth, L., Malamy, M.H., Allewell, N.M. and Tuchman, M. Structure and catalytic mechanism of a novel N-succinyl-L-ornithine transcarbamylase in arginine biosynthesis of Bacteroides fragilis. J. Biol. Chem. 281 (2006) 20623-20631. [PMID: 16704984]

2. Shi, D., Yu, X., Cabrera-Luque, J., Chen, T.Y., Roth, L., Morizono, H., Allewell, N.M. and Tuchman, M. A single mutation in the active site swaps the substrate specificity of N-acetyl-L-ornithine transcarbamylase and N-succinyl-L-ornithine transcarbamylase. <>Protein Sci. 16 (2007) 1689-1699. [PMID: 17600144]

[EC created 2008]

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