RRC ID 35774
Author Ishikawa K, Takeuchi N, Takahashi S, Matera KM, Sato M, Shibahara S, Rousseau DL, Ikeda-Saito M, Yoshida T.
Title Heme oxygenase-2. Properties of the heme complex of the purified tryptic fragment of recombinant human heme oxygenase-2.
Journal J Biol Chem
Abstract Recombinant human microsomal heme oxygenase-2 was expressed in Escherichia coli. Tryptic digestion of the membrane fraction, in which the wild-type enzyme was localized, yielded a soluble tryptic peptide of 28 kDa, which retained the ability to accept electrons from NADPH-cytochrome P-450 reductase and the enzymatic activity for conversion of heme to biliverdin. The tryptic fragment, when purified to apparent homogeneity, bound one equivalent of heme to form a substrate-enzyme complex that had spectroscopic properties characteristic of heme proteins, such as myoglobin and hemoglobin. Optical absorption, Raman scattering, and EPR studies of the heme-tryptic fragment complex revealed that the ferric heme was six coordinate high spin at neutral pH and six coordinate low spin at alkaline pH, with a pK alpha value of 8.5. EPR and Raman scattering studies indicated that a neutral imidazole of a histidine residue served as the proximal ligand in the heme-heme oxygenase-2 fragment complex. The reaction with hydrogen peroxide converted the heme of the heme oxygenase-2 fragment complex into a verdoheme-like intermediate, while the reaction with m-chloroperbenzoic acid yielded a oxoferryl species. These spectroscopic properties are similar to those obtained for heme oxygenase-1, and thus the catalytic mechanism of heme oxygenase-2 appears to be similar to that of heme oxygenase-1.
Volume 270(11)
Pages 6345-50
Published 1995-3-17
DOI 10.1074/jbc.270.11.6345
PMID 7890772
MeSH Amino Acid Sequence Animals Base Sequence Cloning, Molecular DNA, Complementary Electron Spin Resonance Spectroscopy Escherichia coli Heme / chemistry Heme / metabolism* Heme Oxygenase (Decyclizing) / biosynthesis Heme Oxygenase (Decyclizing) / chemistry* Heme Oxygenase (Decyclizing) / metabolism* Humans Hydrogen-Ion Concentration Isoenzymes / biosynthesis Isoenzymes / chemistry Isoenzymes / metabolism Kinetics Microsomes / enzymology Molecular Sequence Data Oligodeoxyribonucleotides Peptide Fragments / chemistry Peptide Fragments / metabolism* Protein Conformation* Rabbits Rats Recombinant Proteins / biosynthesis Recombinant Proteins / chemistry Recombinant Proteins / metabolism Sequence Homology, Amino Acid Spectrophotometry Spectrum Analysis, Raman Trypsin
IF 4.106
Times Cited 71
DNA material pHHO2-1 (RDB01671)