EC - L-tryptophan isonitrile synthase

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IntEnz Enzyme Nomenclature


Accepted name:
L-tryptophan isonitrile synthase
Other names:
isnA (gene name)
ambI1 (gene name)
well1 (gene name)
Systematic name:
L-tryptophan:D-ribulose-5-phosphate lyase (isonitrile-forming)



The enzymes from cyanobacteria that belong to the Stigonematales order participate in the biosynthesis of hapalindole-type alkaloids. According to the proposed mechanism, the enzyme forms an imine intermediate composed of linked L-tryptophan and D-ribulose 5-phosphate, followed by loss of the phosphate group and formation of a β-keto imine and keto-enol tautomerization. This is followed by a C-C bond cleavage, the release of acetol, and a retro aldol type reaction that releases formaldehyde and forms the final product [3]. cf. EC, L-tyrosine isonitrile synthase.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Brady, S. F., Clardy, J.
    Cloning and heterologous expression of isocyanide biosynthetic genes from environmental DNA.
    Angew. Chem. Int. Ed. Engl. 44 : 7063-7065 (2005). [PMID: 16206308]
  2. Brady, S. F., Clardy, J.
    Systematic investigation of the Escherichia coli metabolome for the biosynthetic origin of an isocyanide carbon atom.
    Angew. Chem. Int. Ed. Engl. 44 : 7045-7048 (2005). [PMID: 16217820]
  3. Hillwig, M. L., Zhu, Q., Liu, X.
    Biosynthesis of ambiguine indole alkaloids in cyanobacterium Fischerella ambigua.
    ACS Chem. Biol. 9 : 372-377 (2014). [PMID: 24180436]
  4. Chang, W. C., Sanyal, D., Huang, J. L., Ittiamornkul, K., Zhu, Q., Liu, X.
    In Vitro Stepwise Reconstitution of Amino Acid Derived Vinyl Isocyanide Biosynthesis: Detection of an Elusive Intermediate.
    Org. Lett. 19 : 1208-1211 (2017). [PMID: 28212039]

[EC created 2018]