Purification and preliminary characterization of L-asparaginase from Erwinia aroideae NRRL B-138.

L-Asparaginase (L-asparagine amidohydrolase EC 3.5.1.1) from Erwinia aroideae NRRL B-138 has been purified to apparent homogeneity by ammonium sulphate precipitation, chromatography on sulfopropyl-sephadex C-50 and sephadex G-200 with 22% recovery and 567-fold purification. The enzyme obtained from sulfopropyl-sephadex C-50 was unstable and lost activity within a few hours. Addition of glycerol helped in restoring the activity of the enzyme. The enzyme has an apparent molecular mass of approximately 155 kDa and has four subunits of identical molecular mass of approximately 38 kDa. The K(m) for L-asparagine is 2.8 x 10(-3) M. Enzyme shows optimal activity at 45 degrees C and pH 8.2. Energy of activation as determined from Arrhenius plot was 9.1 kcal/mol. Substrate L-asparagine and analogue L-glutamine, D-asparagine and 6 diazo-5-oxo-L-norleucine provide full protection to the enzyme against thermal denaturation.

Purification and characterization of pectin lyase of erwinia dissolvent

Erwinia dissolvens [Code No. E2 F2] was grown in two different media by static culture method for two weeks. The extracellular pectin lyase produced by the organism in Medium I was partially purified by gel filtration chromatography on Sephadex G-75 and Sephadex G-200 while that produced in Medium II was purified by chromatographing on Sephadex G-75, Sephadex G-200, DEAE-cellulose columns. Some characteristics of the enzyme were determined and compared with those of pectin lyases and pectate lyases of bacterial and fungal origins previously reported in the literature