An efficient bacterial expression system of cyanobacterium Synechocystissp. PCC 6803 heme oxygenase gene, ho-1, has been constructed, using a synthetic gene. A soluble protein was expressedat high levels and was highly purified, for the first time. The protein binds equimolar free hemin to catabolize the boundhemin to ferric-bili-verdin IXa in the presence of oxygen andreducing equivalents, showing the heme oxygenase activity. During the reaction, verdoheme intermediate is formed with the evolution of carbon monoxide. .
