Evidence that biliverdin-IXβ reductase and flavin reductase are identical

Abstract

A search of the database shows that human biliverdin-IXβ reductase and flavin reductase are identical. We have isolated flavin reductase from bovine erythrocytes and show that the activity co-elutes with biliverdin-IXβ reductase. Preparations of the enzyme that are electrophoretically homogeneous exhibit both flavin reductase and biliverdin-IXβ reductase activities; however, they are not capable of catalysing the reduction of biliverdin-IXα. Although there is little obvious sequence identity between biliverdin-IXα reductase (BVR-A) and biliverdin-IXβ reductase (BVR-B), they do show weak immunological cross-reactivity. Both enzymes bind to 2´,5´-ADP–Sepharose.