title: Flavin-photosensitized monomerization of dimethylthymine cyclobutane dimer in the presence of magnesium perchlorate.
abstract: We have investigated the photosensitized monomerization of the cis,syn-cyclobutane dimer of 1,3-dimethylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction.
authors.affiliation: Department of Chemical Process Engineering, Faculty of Engineering, Osaka University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Miyake
authors.forename: Y
authors.initials: Y
authors.lastname: Masaki
authors.forename: I
authors.initials: I
authors.lastname: Miyamoto
authors.forename: S
authors.initials: S
authors.lastname: Yanagida
authors.forename: T
authors.initials: T
authors.lastname: Ohno
authors.forename: A
authors.initials: A
authors.lastname: Yoshimura
authors.forename: C
authors.initials: C
authors.lastname: Pac
mesh_terms: D005415:Flavins / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D010472:Perchlorates / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D011740:Pyrimidine Dimers / Q000737:chemistry / Q000528:radiation effects*; D012256:Riboflavin / Q000737:chemistry; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D005415:Flavins; D017616:Magnesium Compounds; D010472:Perchlorates; D017319:Photosensitizing Agents; D011740:Pyrimidine Dimers; C019319:5-deazaflavin; C039199:N,N-dimethylthymine; C016547:magnesium perchlorate; D013941:Thymine; D012256:Riboflavin