Literature summary for 4.1.99.13 extracted from

Iwai, S.; Mizukoshi, T.; Hitomi, K.; Todo, T.
Chemical synthesis of oligonucleotides containing the (6-4) photoproduct at the thymine-cytosine site and its repair by (6-4) photolyase (1999), Nucleosides Nucleotides, 18, 1325-1327.

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Organism

Organism	UniProt	Comment	Textmining
Xenopus laevis	-	-	-

Reaction

Reaction	Comment	Organism	Reaction ID
(6-4) photoproduct (in DNA) = 2 pyrimidine residues (in DNA)	The overall repair reaction consists of two distinct steps, one of which is light-independent and the other one light-dependent. In the initial light-independent step, a 6-iminium ion is thought to be generated via proton transfer induced by two histidines highly conserved among the (6-4) photolyases.This intermediate spontaneously rearranges to form an oxetane intermediate by intramolecular nucleophilic attack. In the subsequent light-driven reaction, one electron is believed to be transferred from the fully reduced FAD cofactor (FADH-) to the oxetane intermediate thus forming a neutral FADH radical and an anionic oxetane radical, which spontaneously fractures. The excess electron is then back-transferred to the flavin radical restoring the fully reduced flavin cofactor and a pair of pyrimidine bases	Xenopus laevis	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
T(6-4)C photoproduct (in DNA)	A T(6-4)C photoproduct is synthesized. Differences from T(6-4)T is formation of cytosine hydrates by UV irradiation, and acylation of the amino function with the capping reagent. The capping step is omitted to improve the yield of the desired oligonucleotides. (6-4) photolyase restores the pyrimidines in T(6-4)C to their original structures	Xenopus laevis	T-C (in DNA)	-	?

Synonyms

Synonyms	Comment	Organism
(6-4) photolyase	-	Xenopus laevis

Cofactor

Cofactor	Comment	Organism	Structure
FAD	-	Xenopus laevis

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Release 2023.1 (January 2023)