Identification of the Product of Heme Degradation Catalyzed by the Heme Oxygenase System as Biliverdin IXα by Reversed-Phase High-Performance Liquid Chromatography

Biliverdins formed from heme by a microsomal preparation and a reconstituted heme oxygenase system were each converted to their dimethyl esters and analyzed for isomeric composition by reversed-phase high-performance liquid chromatog raphy, using a column of ƒEBondapak C18 (Waters Associates); on this column, the dimethyl esters of four biliverdin ‡\ isomers, that is ‡\ƒ?, ‡\ƒA, ‡\ƒA, and ‡\ƒÂ, have been shown to be eluted separately in the order ‡\ƒ?, ‡\ƒA, ‡\ƒÂ, and ‡\ƒA, when developed with methanol/water. The analysis indicated that the enzymatically formed biliverdins were exclusively ‡\ƒ?; the elution profile exhibited no other significant elution peak due to other biliverdin isomers. It was concluded that the heme oxygenase system cleaves the heme ring specifically at the ƒ?-methene bridge to yield biliverdin ‡\ƒ?.