Crystallization as a purification method for jack bean urease:: On the suitability of Poly(Ethylene glycol), Li2SO4, and NaCl as precipitants

The purification of urease from jack bean meal by means of extraction and crystallization in the presence of different precipitants has been investigated. Purification with poly(ethylene glycol) proves to be a promising alternative to established methods. Although lower yields and purities were observed when compared to Sumner's method, a suitable combination of process parameter changes has the potential to match or even exceed the product qualities previously obtained. Moreover, poly(ethylene glycol) shows promise as a washing liquid for the final crystal product. In contrast to extraction and crystallization of urease in the presence of acetone, the additive 2-mercaptoethanol has a detrimental effect upon product quality in the case presented here. The salts lithium sulfate and sodium chloride show no effective selective precipitation or crystallization of jack bean proteins.