Arginine Deiminase(ADI) was purified to homogeneity using ammonium sulfate precipitation,Q-Sepharose Fast Flow anion exchange chromatography and SephadexG-75 gel filtration chromatography. This purification protocol resulted in a 34.5-fold purification of ADI with 31.4% final yield. A molecular weight of about 190 kD determined by native gradient polyacrylamide gel electrophoresis. The enzyme has only one kind of 46 kD subunit determined by SDS-PAGE. Combining the results from the two kinds of electrophoresis,the authors deduce that the enzyme may be a tetramer. The optimum pH and temperature for lipolytic activity of ADI was pH 6.5 and 50℃,respectively. It was extremely stable at 45℃ and retained 97.9% of its original activity for 30 min. The stability declined rapidly as soon as the temperature rose over 50℃. ADI was highly stable in the pH range from pH 5-8. ADI acted on L-arginine but not on D-arginine. ADI catabolism was dependent on metal ions. At their adequate concentration,Mn2+,Mg2+ and Co2+ were the effective promoter,while superfluous Zn2+and Co2+ inhibited ADI activity. L-citrulline did not act on ADI,but L-ornithine inhibited ADI activity. The degradation of L-arginine with ADI catalysis was according to simple Michaelis-Menten equation. The Michaelis constant was 3.2686 mmol/L and the maxi-mum velocity was 2.44 μmol/min.

Extraction of arginine deiminase(ADI) from NJ402 using aqueous two-phase system(ATPS) provides a method for purification of arginine deiminase.The aqueous two-phase system(ATPS) is composed of polyethylene glycol(PEG) and(NH4)2SO4.Approximately 91.1% of arginine deiminase with the purification factor of 2.35 could be extracted from NJ402 under the optimal conditions that the average relative molecular mass of PEG is 1000,w(PEG1000)=15%,w[(NH4)2SO4]=20%,and pH=6.5 at room temperature.

The result of extraction of arginine deiminase(ADI) using reversed micellar system is reported,which provides a method for the purification of arginine deiminase.In the system,cetyltrimethylammonium bromide(CTAB) was used as surfactant,octane was used as solvent and butanol was used as co-solvent.The optimum conditions were established that the concentration of CTAB is controlled at 0.01 mol/L,pH at 7,shaking time at 15 minutes,the concentration of NaCl at 0.75 mol/L,and the initial enzyme mass concentration at 30 g/L.The yield of ADI can reach 85%,while the specific activity can reach 1.107 U/mg which is 4.52 times that of the original deiminase.