Separation of Papain and Dextran of Similar Molecular Weights by Ultrafiltration

概要

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Ultrafiltration, a useful technique in biological process, is unsuitable for the separation of solutes of similar molecular weights. If the sizes of the solutes are changeable, however, their separation may be possible. Salting in and salting out result from the change of state of a solute with hte concentration of coexisting salt. The application of these phenomena to modification of the characteristics of ultrafiltration was examined. The ultrafiltration of papain (MW 23,400) and dextran (MW 19,600) as single solutes and as a mixture was carried out in a stirred-type ultraifiltration cell with a membrane having a molecular weight cut-off of 100,000. With single solutes, the ultrafiltration characteristics of papain and dextran were different, even when their concentrations were lower than their solubilities; the rejection coefficients for papain were much larger than for dextran. In the ultrafiltration of the mixture at a salt concentration of 25 w/w%, not only papain but a part of the dextran was retained in the retentate solution. At a salt concentration of 8 w/w%, however, dextran was deriven through with the permeate solution but the rejection coefficient for papain was high. Thus, in spite of their similar molecular weights, papain and dextran are separable by ultrafiltration by changing their sizes in the solution.
社団法人日本生物工学会の論文
1993-09-25