Study of amine oxidases from cereal seedlings and local plants

Occurrence of aliphatic amines is widespread in plant cells. These compounds are implicated in regulation of plant growth and development and biotic and abiotic stress responses. The intracellular free aliphatic amines pool depends on synthesis and several other processes, including degradation, conjugation and transport. Aliphatic amines can be oxidatively degraded in higher plants, by the action of amine oxidases. Enzymes involved in aliphatic amines catabolism and products derived from their action are involved in important plant physiological processes. The present paper describes the partial characterization of amine oxidases and compare the properties with those of the pea, maize seedlings and other plant enzymes. Enzyme extraction were studied to evaluate the activity of monoamine oxidase and diamine oxidase from cereal seedling, green tea leaves and ginger. Reaction of amine oxidases with ethylamine and putrescine were compared to determine monoamine oxidase and diamine oxidase activities. The results showed that the enzyme activities were in the pH range of 6.0-8.0 and the optimum pH was 7.5 for both enzymes. Both amine oxidases were thermal labile at temperature more than 50 deg C. The specific activities of monoamine oxidase were 0.33, 0.36, 1.26, 1.43 and 3.12 U/mg protein for the enzyme from the mung bean, green tea leaves, maize, soybean and ginger, respectively. The specific activities for diamine oxidase were 0.22, 0.70, 1.43, 2.81 and 2.94 U/mg protein for the enzyme from the green tea leaves, mung bean, maize, ginger and soybean, respectively. This suggests that ginger contained monoamine oxidase more than the others while the maize and ginger contained diamine oxidase more than the others. However ginger contained higher both monoamine oxidase (151.46 U/g dry wieght) and diamine oxidase (156.75 U/g dry weight) more than the others. This study indicates similar properties of the enzymes but the different levels of both enzymes in plants.