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Irreversible conversion of xanthine dehydrogenase into xanthine oxidase by a mitochondrial protease
Author(s) -
Saksela Mika,
Lapatto Risto,
Raivio Kari O
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01686-x
Subject(s) - xanthine dehydrogenase , biochemistry , xanthine oxidase , proteases , cytosol , intermembrane space , chemistry , protease , enzyme , mitochondrion , escherichia coli , bacterial outer membrane , gene
Irreversible conversion of xanthine dehydrogenase (XDH) to its oxygen free radical producing oxidase (XO) form occurs through an uncharacterized proteolytic process, which was studied in human liver. Upon incubation of fresh unfrozen liver cytosol, XDH remained intact. When recombinant human XDH was coincubated with subcellular fractions of human liver, the mitochondrial intermembrane space was shown to contain a heat‐labile activity that converted XDH irreversibly to XO. This activity is resistant to inhibitors of all major groups of proteases. We postulate that this novel type of proteolytic enzyme is released into the cytosol upon mitochondrial damage.