Primary structures for a mammalian cellular and serum copper amine oxidase.

The 6-hydroxydopa quinone-containing active site peptide from bovine serum amine oxidase has been found to be highly homologous to a segment of a cloned human kidney amiloride-binding protein (Barbry, P., Champe, M., Chassande, O., Munemitsu, S., Champigny, G., Lingueglia, E., Maes, P., Frelin, C., Tartar, A., Ullrich, A., and Lazdunski, M. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7347-7351). Additionally, a second 38-residue tryptic peptide (peptide XI) isolated from bovine serum amine oxidase shows 82% identity with a portion near the carboxyl terminus of the human kidney amiloride-binding protein. When an extended active site peptide was isolated from porcine kidney diamine oxidase (Janes, S. M., Palcic, M. M., Scaman, C. H., Smith, A. J., Brown, D. E., Dooley, D. M., Mure, M., and Klinman, J. P. (1992) Biochemistry 31, 12147-12154), it was found to be fully contained in the human kidney amiloride-binding protein. Examination of amiloride binding to bovine serum amine oxidase and porcine kidney diamine oxidase reveals dissociation constants of 196 and 9.1 microM, respectively. Taken together, these findings indicate that the cDNA isolated for human kidney amiloride-binding protein encodes a human kidney diamine oxidase. Two oligonucleotides, based on the tryptic peptide XI and active-site peptide of bovine serum amine oxidase, were used to amplify a portion of cDNA from a commercial bovine liver cDNA library through the use of the polymerase chain reaction. A full-length clone (2.7 kilobase pairs) for bovine serum amine oxidase was subsequently obtained through screening of the same cDNA library with the amplified 0.7-kilobase pair cDNA. These studies provide the first primary sequences for a mammalian cellular and serum copper amine oxidase. Computer alignment of amine oxidase cDNA-derived protein sequences reveals three conserved histidine residues, which are likely to be ligands to copper.