Substrate electric dipole moment exerts a pH-dependent effect on electron transfer in Escherichia coli photolyase.
J Am Chem Soc
; 126(20): 6214-5, 2004 May 26.
Article
en En
| MEDLINE
| ID: mdl-15149202
Transient absorption spectroscopy is used to demonstrate that the electric dipole moment of the substrate cyclobutane thymine dimer affects the charge recombination reaction between fully reduced flavin adenine dinucleotide (FADH-) and the neutral radical tryptophan 306 (Trp306*) in Escherichia coli DNA photolyase. At pH 7.4, the charge recombination is slowed by a factor of 1.75 in the presence of substrate, but not at pH 5.4. Photolyase does bind substrate at pH 5.4, and it seems that this pH effect originates from the conversion of FADH- to FADH2 at lower pH. The free-energy changes calculated from the electric field parameters and from the change in electron transfer rate are in good agreement and support the idea that the substrate electric dipole is responsible for the observed change in electron transfer rate. It is expected that the substrate electric field will also modify the physiologically important from excited 1FADH- to the substrate in the DNA repair reaction.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Desoxirribodipirimidina Fotoliasa
/
Escherichia coli
Idioma:
En
Revista:
J Am Chem Soc
Año:
2004
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos