Agmatine deiminase in rice seedlings

Agmatine deiminase activity in rice embryos increased gradually upto 24 hr during germination and then decreased. Gibberellic acid and kinetin inhibited the activity when added to the germination medium. The enzyme was purified 717 fold with specific activity 788.5 nkat/mg protein and yield 8.8%. The M_r of the native enzyme was 18.3 x 10⁴ and the enzyme was a dimer of two identical subunits. The pH and temperature optimum of the enzyme were 6.0 and 28° respectively. The enzyme followed typical Michaelis-Menten kinetics with a K_m value of 1.5 x 10^?2 M. The enzyme activity was inhibited by various divalent cations and spermidine and spermine, but putrescine showed no effect.