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Heme oxygenase converts heme into biliverdin, CO, and free iron. In plants, as well as in cyanobacteria, heme oxygenase plays a particular role in the biosynthesis of photoreceptive pigments, such as phytochromobilins and phycobilins, supplying biliverdin IXaas a direct synthetic resource. | ễFEBS Journal Spectroscopic characterization of a higher plant heme oxygenase isoform-1 from Glycine max soybean -coordination structure of the heme complex and catabolism of heme Tomohiko Gohya1 Xuhong Zhang2 Tadashi Yoshida2 and Catharina T. Migita1 1 Department of BiologicalChemistry Faculty of Agriculture Yamaguchi University Japan 2 Department of Biochemistry Yamagata University Schoolof Medicine Japan Keywords ferredoxin heme catabolism heme complex higher-plant heme oxygenase spectroscopic characterization Correspondence C. T. Migita Department of Biological Chemistry Faculty of Agriculture Yamaguchi University 1677-1 Yoshida Yamaguchi 753-8515 Japan Fax Tel 81 83 9335863 E-mail ctmigita@yamaguchi-u.ac.jp T. Yoshida Department of Biochemistry Yamagata University Schoolof Medicine lidanishi 2-2-2 Yamagata 990-9585 Japan Fax 81 23 6285225 Tel 81 23 6285222 E-mail tyoshida@med.id.yamagata-u.ac.jp Received 9 August 2006 revised 1 October 2006 accepted 9 October 2006 doi 10.1111 j.1742-4658.2006.05531.x Heme oxygenase converts heme into biliverdin CO and free iron. In plants as well as in cyanobacteria heme oxygenase plays a particular role in the biosynthesis of photoreceptive pigments such as phytochromobilins and phycobilins supplying biliverdin IXa as a direct synthetic resource. In this study a higher plant heme oxygenase GmHO-1 of Glycine max soybean was prepared to evaluate the molecular features of its heme complex the enzymatic activity and the mechanism of heme conversion. The similarity in the amino acid sequence between GmHO-1 and heme oxygenases from other biological species is low and GmHO-1 binds heme with 1 1 stoichiometry at His30 this position does not correspond to the proximal histidine of other heme oxygenases in their sequence alignments. The heme bound to GmHO-1 in the ferric high-spin state exhibits an acidbase transition and is converted to biliverdin IXa in the presence of NADPH ferredoxin reductase ferredoxin or ascorbate. During the .
