IUBMB Enzyme Nomenclature


Accepted name: purine imidazole-ring cyclase

Reaction: DNA 4,6-diamino-5-formamidopyrimidine = DNA adenine + H2O

Other name(s): DNA-4,6-diamino-5-formamidopyrimidine C8-N9-lyase (cyclizing); DNA-4,6-diamino-5-formamidopyrimidine 8-C,9-N-lyase (cyclizing)

Systematic name: DNA-4,6-diamino-5-formamidopyrimidine C8-N9-lyase (cyclizing; DNA-adenine-forming)

Comments: Also acts on 2,6-diamino-5-formamido-3,4-dihydro-4-oxopyrimidine residues. Brings about the reclosure of the imidazole rings of purine residues damaged by γ-rays.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 95990-28-6


1. Chetsanga, C.J. and Grigorian, C. In situ enzymatic reclosure of opened imidazole rings of purines in DNA damaged by γ-irradiation. Proc. Natl. Acad. Sci. USA 82 (1985) 633-637. [PMID: 3856219]

[EC created 1989]

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