Purification and characterization of L-asparaginase from erwinia carotovora

An L-asparaginase from Erwinia carotovora was successively purified by ammonium sulfate precipitation, DEAE-cellulose and Sephacryl S-200 columns. The specific activity of the L-asparaginase was increased approximately 55-fold, from 15.5 to 852 U/mg proteins. SDS-PAGE showed that the purified L-asparaginase was homogeneous and the molecular weight was about 115 kDa. The isoelectric point [pI] of the enzyme was about 5.9. Characterization of the enzyme exhibited optimum pH and temperature of 8.4 and 40°C, respectively. The purified enzyme is able to prolong its thermal stability up to 50°C. A Lineweaver-Burk analysis showed a K[m] value of 0.154 mM and V[max] of 41.67 U. The purified enzyme was rich in glycine, alanine, glutamic acid and aspartic acid

Production, partial purification and characterization of dextransucrase from leuconostoc mesenteroides NRRL B-512F

Dextransucrase enzyme from Leuconostoc mesenteroides NRRL B-512F was studied. The results showed that highest enzyme yield was obtained by growing the bacterium in shake culture flasks [250 ml capacity] containing 50 ml of culture medium having sucrose as a sole carbon source [at a concentration of 4%] with initial pH of 7.0 for 48 hr at 30°C using an inoculum size of 5%. Pretreated molasses from sugarcane and beet were used as carbon source and they showed a considerable activity in relation to sucrose. Partial purification by ammonium sulfate precipitation and column chromatography were studied. Both the degree of purity and the approximate molecular weight of the enzyme were studied using SDS-PAGE. The enzyme showed one band with a molecular weight of about 68 kDa. The partial purified enzyme exhibited its optimum activity at a temperature of 35 °C and a pH of 5.0