Table 2. In vitro assay showing substrate specificity.

Substrate	Product assayed	Polyamine oxidase activity, nmol per mg of protein per min
Spermine	Spermidine	390
N1-Acetylspermine	Spermidine	800
N1-Acetylspermidine	Putrescine	270

Substrates (1 mM) were incubated in the presence of partially purified (≈80%) His-tagged Fms1 protein as mentioned in Materials and Methods, and, after 30 min, reactions were stopped. Activity was measured on the basis of amine conversion (appearance of amine product) as determined by HPLC analysis. No oxidation was observed by using spermidine or putrescine as substrate (data not shown).