IUBMB Enzyme Nomenclature


Accepted name: asparagine synthase (glutamine-hydrolysing)

Reaction: ATP + L-aspartate + L-glutamine + H2O = AMP + diphosphate + L-asparagine + L-glutamate (overall reaction)
(1a) L-glutamine + H2O = L-glutamate + NH3
(1b) ATP + L-aspartate + NH3 = AMP + diphosphate + L-asparagine

Other name(s): asparagine synthetase (glutamine-hydrolysing); glutamine-dependent asparagine synthetase; asparagine synthetase B; AS; AS-B

Systematic name: L-aspartate:L-glutamine amido-ligase (AMP-forming)

Comments: The enzyme from Escherichia coli has two active sites [4] that are connected by an intramolecular ammonia tunnel [6,7]. The enzyme catalyses three distinct chemical reactions: glutamine hydrolysis to yield ammonia takes place in the N-terminal domain. The C-terminal active site mediates both the synthesis of a β-aspartyl-AMP intermediate and its subsequent reaction with ammonia. The ammonia released is channeled to the other active site to yield asparagine [7].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37318-72-2


1. Patterson, M.K., Jr. and Orr, G.R. Asparagine biosynthesis by the Novikoff hepatoma. Isolation, purification, property, and mechanism studies of the enzyme system. J. Biol. Chem. 243 (1968) 376-380. [PMID: 4295091]

2. Boehlein, S.K., Richards, N.G. and Schuster, S.M. Glutamine-dependent nitrogen transfer in Escherichia coli asparagine synthetase B. Searching for the catalytic triad. J. Biol. Chem. 269 (1994) 7450-7457. [PMID: 7907328]

3. Richards, N.G. and Schuster, S.M. Mechanistic issues in asparagine synthetase catalysis. Adv. Enzymol. Relat. Areas Mol. Biol. 72 (1998) 145-198. [PMID: 9559053]

4. Larsen, T.M., Boehlein, S.K., Schuster, S.M., Richards, N.G., Thoden, J.B., Holden, H.M. and Rayment, I. Three-dimensional structure of Escherichia coli asparagine synthetase B: a short journey from substrate to product. Biochemistry 38 (1999) 16146-16157. [PMID: 10587437]

5. Huang, X., Holden, H.M. and Raushel, F.M. Channeling of substrates and intermediates in enzyme-catalyzed reactions. Annu. Rev. Biochem. 70 (2001) 149-180. [PMID: 11395405]

6. Tesson, A.R., Soper, T.S., Ciustea, M. and Richards, N.G. Revisiting the steady state kinetic mechanism of glutamine-dependent asparagine synthetase from Escherichia coli. Arch. Biochem. Biophys. 413 (2003) 23-31. [PMID: 12706338]

[EC created 1972, modified 2006]

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