Identification of Flavin Adenine Dinucleotide and Heme in a Homogeneous Spermidine Dehydrogenase from Serratia marcescens

Spermidine dehydrogenase has been purified 5,000-fold to homogeneity from extracts of Serratia marcescens. The molecular weight is 76,000; no evidence has been obtained for subunits. The spectrum of the enzyme is characteristic of a heme protein. Both iron-protoporphyrin IX and flavin adenine dinucleotide have been identified in the enzyme in a molar ratio of heme to FAD to enzyme protein of approximately 0.8:0.9:1.0.