Open AccessIdentification of an N‐hydroxyguanidine reducing activity of xanthine oxidase
Author(s) -
Dambrova Maija,
Uhlén Staffan,
Welch Christopher J.,
Wikberg Jarl E. S.
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2570178.x
Subject(s) - xanthine oxidase , chemistry , allopurinol , biochemistry , xanthine , enzyme , xanthine dehydrogenase , enzyme assay , oxidase test , reducing agent , organic chemistry , medicine , pathology
A guanoxabenz [1‐(2,6‐dichlorobenzylideneamino)‐3‐hydroxyguanidine; an N‐hydroxyguanidine] reducing enzymatic activity of rat spleen cytosol was investigated. By means of protein purification and N‐terminal amino acid sequencing, the reducing activity was shown to reside in xanthine oxidase. The action of the enzyme on guanoxabenz resulted in the formation of guanabenz [1‐(2,6‐dichlorobenzylideneamino)‐3‐guanidine]; the product formation could be monitored by HPLC and its identity was confirmed by NMR analysis. The reduction of guanoxabenz required xanthine or NADH as reducing substrates, while the process could be blocked by allopurinol, a selective inhibitor of xanthine oxidase. By using bovine milk xanthine oxidase, the guanoxabenz reducing activity of the enzyme was also verified. We conclude that guanoxabenz is a novel electron acceptor structure for xanthine oxidase.