Photoreactivation of alloxanthine-inhibited xanthine oxidase

Authors
Citation
La. Tai et Kc. Hwang, Photoreactivation of alloxanthine-inhibited xanthine oxidase, PHOTOCHEM P, 73(4), 2001, pp. 439-446
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
PHOTOCHEMISTRY AND PHOTOBIOLOGY
ISSN journal
0031-8655 → ACNP
Volume
73
Issue
4
Year of publication
2001
Pages
439 - 446
Database
ISI
SICI code
0031-8655(200104)73:4<439:POAXO>2.0.ZU;2-N
Abstract
Alloxanthine-inhibited xanthine oxidase (XOD) was found to be photoreactiva ted by irradiation of light of wavelengths in the range of 340-430 nm. The enzyme activity can be fully controlled to be on or off by many dark-light cycles. Electron spin resonance measurement shows the appearance of the mol ybdenum (V) ion and the reduced form of flavin adenine dinucleotide (FADH.) radical signals after irradiation of the alloxanthine-XOD complex. Electro nic-absorption spectrum also shows the bleaching of Fe/S and flavin adenine dinucleotide chromophores at 375 and 450 nm as well as broad-band absorpti on of FADH(.) in the range of 500-700 nm. The quantum yield of photoreactiv ation of the enzyme activity is similar to0.06. A photoinduced intraenzyme electron-transfer model is proposed to rationalize the photoreactivation pr ocess.