Estimation of endoglucanase and lysozyme effective diffusion coefficients in polysulphone membranes

A diffusion cell and a polysulphone membrane were used for the estimation o f the effective diffusion coefficient (D-M) of endoglucanase and lysozyme. D-M was calculated from the slope obtained by fitting the amount of protein transferred through the membrane against time using the appropriate mathem atical equation for the steady state. Different protein concentrations and pH values were tested. The calculated D-M for endoglucanase was in the orde r of 10(-13) m(2) s(-1) whereas the calculated D-M for lysozyme was an orde r of magnitude lower. A diffusion coefficient dependence on the concentrati on and pH was observed. In addition, the partition coefficient, K-M, of the two proteins between the membrane and a solution containing the proteins w as calculated. (C) 1999 Elsevier Science B.V. All rights reserved.