title: Arabidopsis thaliana peroxidase N: structure of a novel neutral peroxidase.
abstract: The structure of the neutral peroxidase from Arabidopsis thaliana (ATP N) has been determined to a resolution of 1.9 A and a free R value of 20.5%. ATP N has the expected characteristic fold of the class III peroxidases, with a C(alpha) r.m.s.d. of 0.82 A when compared with horseradish peroxidase C (HRP C). HRP C is 54% identical to ATP N in sequence. When the structures of four class III plant peroxidases are superimposed, the regions with structural differences are non-randomly distributed; all are located in one half of the molecule. The architecture of the haem pocket of ATP N is very similar to that of HRP C, in agreement with the low small-molecule substrate specificity of all class III peroxidases. The structure of ATP N suggests that the pH dependence of the substrate turnover will differ from that of HRP C owing to differences in polarity of the residues in the substrate-access channel. Since there are fewer hydrogen bonds to haem C17 propionate O atoms in ATP N than in HRP C, it is suggested that ATP N will lose haem more easily than HRP C. Unlike almost all other class III plant peroxidases, ATP N has a free cysteine residue at a similar position to the suggested secondary substrate-binding site in lignin peroxidase.
authors.affiliation: Protein Structure Group, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Kobenhavn O, Denmark.
authors.forename: O
authors.initials: O
authors.lastname: Mirza
authors.forename: A
authors.initials: A
authors.lastname: Henriksen
authors.forename: L
authors.initials: L
authors.lastname: Ostergaard
authors.forename: K G
authors.initials: KG
authors.lastname: Welinder
authors.forename: M
authors.initials: M
authors.lastname: Gajhede
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000737:chemistry* / Q000302:isolation & purification; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D010544:Peroxidases; C107607:neutral peroxidase, plant