Literature summary extracted from

Zhao, X.; Liu, J.; Hsu, D.S.; Zhao, S.; Taylor, J.S.; Sancar, A.
Reaction mechanism of (6-4) photolyase (1997), J. Biol. Chem., 272, 32580-32590.

Activating Compound

EC Number	Activating Compound	Comment	Organism	Structure
4.1.99.13	Dithionite	reduction of the FAD cofactor with dithionite increases the quantum yield of repair	Drosophila melanogaster

Cloned(Commentary)

EC Number	Cloned (Comment)	Organism
4.1.99.13	expressed in Escherichia coli as a MBP-PL-(6-4) fusion protein	Drosophila melanogaster

Organism

EC Number	Organism	UniProt	Comment	Textmining
4.1.99.13	Drosophila melanogaster	-	-	-

Purification (Commentary)

EC Number	Purification (Comment)	Organism
4.1.99.13	fusion protein is purified through a 20-ml amylose column and through heparin-agarose column	Drosophila melanogaster

Reaction

EC Number	Reaction	Comment	Organism	Reaction ID
4.1.99.13	(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	Drosophila melanogaster	a

Substrates and Products (Substrate)

EC Number	Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
4.1.99.13	additional information	binding and catalytic properties of the enzyme are investigated using natural substrates, T[6-4]T and T[6-4]C, and the Dewar isomer of (6-4) photoproduct and substrate analogs s5T[6-4]T/thietane, mes5T[6-4]T, and the N-methyl-3T thietane analog of the oxetane intermediate. The enzyme binds to the natural substrates and to mes5T[6-4]T with high affinity and produces a DNase I footprint of about 20 base pairs around the photolesion. Of the four substrates that bind with high affinity to the enzyme, T[6-4]T and T[6-4]C are repaired with relatively high quantum yields compared with the Dewar isomer and the mes5T[6-4]T which are repaired with 300-400-fold lower quantum yield	Drosophila melanogaster	?	-	?

Synonyms

EC Number	Synonyms	Comment	Organism
4.1.99.13	(6-4) photolyase	-	Drosophila melanogaster
4.1.99.13	PL-(6-4)	-	Drosophila melanogaster

Cofactor

EC Number	Cofactor	Comment	Organism	Structure
4.1.99.13	FAD	-	Drosophila melanogaster

Use of this online version of BRENDA is free under the CC BY 4.0 license. See terms of use for full details.

Release 2023.1 (January 2023)