Ornithine decarboxylase (ODC, EC 4.1.1.17) is a key enzyme that catalyzes the synthesis of free polyamines in most plants and is associated with plant stress physiology.
Ornithine decarboxylase catalyzes the conversion of the substrate ornithine to putrescine. The product putrescine is derivatized using a derivatizing agent, and the derivative exhibits a maximum absorption peak at 254 nm. ODC enzyme activity is determined by measuring the change in absorbance at 254 nm.