title: Plant peroxidases. Their primary, secondary and tertiary structures, and relation to cytochrome c peroxidase.
abstract: The amino acid sequences of the 51% different horseradish peroxidase HRP C and turnip peroxidase TP 7 have previously been completed by us, but the three-dimensional structures are unknown. Recently the amino acid sequence and the crystal structure of yeast cytochrome c peroxidase have appeared. The three known apoperoxidases consist of 300 +/- 8 amino acid residues. The sequences have now been aligned and show 18% and 16% identity only, between the yeast peroxidase and plant peroxidase HRP C and TP 7, respectively. We show that different structural tests all support similar protein folds in plant peroxidases and yeast peroxidase and, therefore, a common evolutionary origin. The following tests support this thesis: (a) predicted helices in the plant peroxidases follow the complex pattern observed in the crystal structure of cytochrome c peroxidase; (b) their hydropathic profiles are similar and agree with observed buried and exposed peptide chain in cytochrome c peroxidase; (c) half-cystines which are distant in the amino acid sequence of plant peroxidases become spatial neighbours when fitted into the cytochrome c peroxidase model; (d) the two-domain structure proposed from limited proteolysis of apoperoxidase HRP C is observed in the crystal structure of cytochrome c peroxidase. The similarities and differences of the plant and yeast peroxidases and the reactive side chains of a plant peroxidase active site are described. The characteristics of Ca2+-binding sequences, derived from several superfamilies, are applied to predict the Ca2+-binding sequences in plant peroxidases.
authors.forename: K G
authors.initials: KG
authors.lastname: Welinder
mesh_terms: D000595:Amino Acid Sequence; D001051:Apoenzymes; D001665:Binding Sites; D002118:Calcium / Q000032:analysis; D002135:Calcium-Binding Proteins; D002241:Carbohydrates / Q000032:analysis; D003553:Cystine / Q000032:analysis; D003578:Cytochrome-c Peroxidase; D006420:Hemeproteins; D008958:Models, Molecular; D010446:Peptide Fragments / Q000032:analysis; D010544:Peroxidases; D010944:Plants / Q000201:enzymology*; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology
chemical_list: D001051:Apoenzymes; D002135:Calcium-Binding Proteins; D002241:Carbohydrates; D006420:Hemeproteins; D010446:Peptide Fragments; D003553:Cystine; D010544:Peroxidases; D003578:Cytochrome-c Peroxidase; D002118:Calcium