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Titolo:
REACTION-MECHANISM OF (6-4)PHOTOLYASE
Autore:
ZHAO XD; LIU JQ; HSU DS; ZHAO SY; TAYLOR JS; SANCAR A;
Indirizzi:
UNIV N CAROLINA,SCH MED,DEPT BIOCHEM & BIOPHYS,CB 7260 CHAPEL HILL NC27599 UNIV N CAROLINA,SCH MED,DEPT BIOCHEM & BIOPHYS CHAPEL HILL NC 27599 WASHINGTON UNIV,DEPT CHEM ST LOUIS MO 63130
Titolo Testata:
The Journal of biological chemistry
fascicolo: 51, volume: 272, anno: 1997,
pagine: 32580 - 32590
SICI:
0021-9258(1997)272:51<32580:RO(>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
(6-4)-PHOTOPRODUCT DNA PHOTOLYASE; BLUE-LIGHT PHOTORECEPTORS; ABSOLUTE ACTION SPECTRUM; TRANSITION-STATE ANALOG; ESCHERICHIA-COLI; SKIN-CANCER; ADENOSINE-DEAMINASE; REPAIR ACTIVITY; TARGET BASE; CIS-SYN;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
58
Recensione:
Indirizzi per estratti:
Citazione:
X.D. Zhao et al., "REACTION-MECHANISM OF (6-4)PHOTOLYASE", The Journal of biological chemistry, 272(51), 1997, pp. 32580-32590

Abstract

The (6-4) photolyase catalyzes the photoreversal of the (6-4) dipyrimidine photoproducts induced in DNA by ultraviolet light, Using the cloned Drosophila melanogaster (6-4) photolyase gene, we overproduced andpurified the recombinant enzyme. The binding and catalytic propertiesof the enzyme were investigated using natural substrates, T[6-4]T andT[6-4]C, and the Dewar isomer of (6-4) photoproduct and substrate analogs s(5)T[6-4]T/thietane, mes(5)T[6-4]T, and the N-methyl-3'T thietane analog of the oxetane intermediate, The enzyme binds to the natural substrates and to mes(5)T[6-4]T with high affinity (K-D similar to 10(-9)-10(-10) M) and produces a DNase I footprint of about 20 base pairsaround the photolesion. Several lines of evidence suggest that upon binding by the enzyme, the photoproduct flips out of the duplex, Of thefour 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 mes(5)T[6-4]T which are repaired with 300-400-fold lower quantum yield than the former two photoproducts. Reduction of the FAD cofactor with dithionite increases the quantum yield of repair. Taken together, the data are consistent with photoinduced electron transfer from reduced FAD to substrate, in a manner analogous to the cyclobutane pyrimidine dimer photolyase.

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Documento generato il 27/01/20 alle ore 07:40:49