Purification and Characterization of Arginine Decarboxylase from Soybean (Glycine max) Hypocotyls

Arginine decarboxylase (EC 4.1.1.19) was purified from soybean, Glycine max, hypocotyls by a procedure which includes ammonium sulfate fractionation, acetone precipitation, gel filtration chromatography, and affinity chromatography. Using this procedure, ADC was purified to one band in non-denaturing PAGE. The purified ADC has an Mr of 240 kDa based on gel filtration chromatography and is a trimer of identical subunits which has an estimated Mr of 74 kDa based on SDS-PAGE. ADC is active between 30 and 50°C and has a Km value of 46.1 μM. ADC is very sensitive to agmatine or putrescine but not to spermidine or spermine. In the presence of 0.5 mM agmatine (or putrescine), the enzyme activity was inhibited by 70%. However, at the same concentration of spermidine (or spermine), the enzyme activity was inhibited by only 10–20%.