ZETA-POTENTIAL STUDY ON THE INTERACTIONS BETWEEN LYSOZYME AND SODIUM N-ALKYLSULFATES

An experimental investigation on the adsorption of n-alkylsulfates wit h 8, 10, 12, 14, and 16 carbon atoms in the alkyl chain length on lyso zyme at pH 3.2, 7.0, and 10.0 by measurements of the zeta potential (z eta-potential) is described. At pH 7.0 and 10.0, the protein surface h as a negative electrokinetic charge while at pH 3.2 the alkylsulfate i ons affect the g-potential causing a change in the neighborhood of the point of zero charge (pzc) from positive to negative values. Values o f the Gibbs energies of adsorption, calculated from the pzc of alkylsu lfates of carbon chain lengths 8, 10, and 12 agree with Gibbs energies of binding of n-alkylsulfates to lysozyme and when compared with the adsorption of n-alkyltrimethyl-ammonium ions show that the headgroup i nteraction is of similar form.