ABSTRACT
The pure protein differs from most other enzymes that oxidize amines in that it is a dehydrogenase with an absolute requirement for an electron carrier. Serratia spermidine dehydrogenase has been utilized for an enzymatic assay for spermidine. The enzyme can be assayed in a crude extract by oxygen utilization or by the reaction of the product Δ-pyrroline with o-aminobenzaldehyde. The enzyme cleaved spermidine specifically between the secondary amino group at position 4 and C-5, yielding diaminopropane and the unstable γ-aminobutyraldehyde, which cyclizes to form Δ -pyrroline. The enzyme appeared to be particulate in a crude extract prepared by sonication in 0.2 M phosphate buffer, pH 7.0, 0.01% mercaptoethanol, and sedimented with the ribosomal fraction. The enzyme reaction was linear with respect to substrate and time. Spermidine dehydrogenase is present in S. marcescens in low concentration.
