Evidence for the hydrophobic cavity of heme oxygenase-1 to be a CO-trapping site.
Carbon monoxide (CO) is produced during the heme catabolism by heme oxygenase. In brain or blood vessels, CO functions as a neurotransmitter or an endothelial-derived relaxing factor. To verify whether crystallographically proposed CO-trapping sites of rat and cyanobacterial heme oxygenase-1 really work, heme catabolism by heme oxygenase-1 from rat and cyanobacterial Synechocystis sp. PCC 6803 has been scrutinized in the presence of 2-propanol. If 2-propanol occupies the trapping sites, formation of CO-bound verdoheme should be enhanced. Although effects of 2-propanol on the rat heme oxygenase-1 reaction were obscure, the reaction of cyanobacterial enzyme in the presence of NADPH/ferredoxin reductase/ferredoxin was apparently affected. Relative amount of CO-verdoheme versus CO-free verdoheme detected by optical absorption spectra increased as the equivalent of 2-propanol increased, thereby supporting indirectly that the hydrophobic cavity in cyanobacterial enzyme traps CO to reduce CO inhibition of verdoheme degradation.
Migita
Catharina T
CT
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi, Japan. ctmigita@yamaguchi-u.ac.jp
Togashi
Satoko
S
Minakawa
Miki
M
Zhang
Xuhong
X
Yoshida
Tadashi
T
D019840:2-Propanol / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D046939:Synechocystis / Q000201:enzymology
D001426:Bacterial Proteins; D008565:Membrane Proteins; D006418:Heme; D002248:Carbon Monoxide; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D019840:2-Propanol; D001205:Ascorbic Acid