Identification and characterization of VPO1, a new animal heme-containing peroxidase

• Published in: Free radical biology & medicine Vol. 45; no. 12; pp. 1682 - 1694
• Main Authors: Cheng, Guangjie, Salerno, John C., Cao, Zehong, Pagano, Patrick J., Lambeth, J. David
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.12.2008
• Subjects: Amino Acid Sequence; Animal heme-containing peroxidase; Animals; Binding Sites; Blotting, Western; Catalysis; Cells, Cultured; Databases, Factual; Enzyme activity; Gene expression; Heme - chemistry; Heme - metabolism; Humans; Hydrogen Peroxide - metabolism; Immunoenzyme Techniques; Kidney - cytology; Kidney - metabolism; Mice; Models, Molecular; Molecular Sequence Data; Myocardium - cytology; Myocardium - metabolism; NADPH oxidase; Peptide Fragments - immunology; Peroxidases - genetics; Peroxidases - immunology; Peroxidases - metabolism; Protein Conformation; Protein structure; Rabbits; Rats; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Tissue Distribution; Transfection; Enzyme activity; EPO; Animal heme-containing peroxidase; ABH; LPO; CTAB; MPO; LRR; TPO; RT-PCR; NADPH oxidase; K m; Noxes; RLU; PBS; NaBu; EST; TMB; SDS–PAGE; Gene expression; PVDF; 5′-RACE; ROS; Duox; HBSS; PGS; Protein structure
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2008.09.009

Animal heme-containing peroxidases play roles in innate immunity, hormone biosynthesis, and the pathogenesis of inflammatory diseases. Using the peroxidase-like domain of Duox1 as a query, we carried out homology searching of the National Center for Biotechnology Information database. Two novel heme-containing peroxidases were identified in humans and mice. One, termed VPO1 for vascular per oxidase 1, exhibits its highest tissue expression in heart and vascular wall. A second, VPO2, present in humans but not in mice, is 63% identical to VPO1 and is highly expressed in heart. The peroxidase homology region of VPO1 shows 42% identity to myeloperoxidase and 57% identity to the insect peroxidase peroxidasin. A molecular model of the VPO1 peroxidase region reveals a structure very similar to that of known peroxidases, including a conserved heme binding cavity, critical catalytic residues, and a calcium binding site. The absorbance spectra of VPO1 are similar to those of lactoperoxidase, and covalent attachment of the heme to VPO1 protein was demonstrated by chemiluminescent heme staining. VPO1 purified from heart or expressed in HEK cells is catalytically active, with a K m for H 2O 2 of 1.5 mM. When co-expressed in cells, VPO1 can use H 2O 2 produced by NADPH oxidase enzymes. VPO1 is likely to carry out peroxidative reactions previously attributed exclusively to myeloperoxidase in the vascular system.