Nucleotide requirements for the bone marrow heme oxygenase system

Rat bone marrow microsomal heme oxygenase activity has been studied and optimal condition for the measurement of this activity are described. The activity of bone marrow heme oxygenase was linear with time and protein concentration as measured under these assay conditions. Bilirubin formation by the heme oxygenase complex system was observed with either a NADPH generating system or with NADH as electron donor. The enzyme activity for heme degradation supported by NADH proceeds at a comparable rate to that observed with NADPH as reducing equivalent. It thus appears that this oxidation reaction must be more complex than simply involving NADPH as the sole election donor as has been previously proposed.