PURIFICATION OF THE BOVINE XANTHINE OXIDOREDUCTASE FROM MILK-FAT GLOBULE MEMBRANES AND CLONING OF COMPLEMENTARY DEOXYRIBONUCLEIC-ACID

The amino acid sequence of the bovine xanthine oxidoreductase was dete rmined by cloning and sequencing cDNA clones encoding the enzyme. Part ial amino acid sequences corresponding to 54% of the total sequence we re also determined from purified bovine milk xanthine oxidoreductase, showing identity with the translated cDNA sequence. The cDNA of 4719 n ucleotides included a 5' untranslated region of 96 nucleotides, an ope n reading frame encoding a xanthine oxidoreductase of 1332 amino acid residues, and a 3' untranslated region of 624 nucleotides including tw o polyadenylation signals and a poly(A) tail of 74 nucleotides. The id entity between the amino acid sequence of the bovine xanthine oxidored uctase and xanthine oxidoreductase from mammalian species was 86 to 90 %.