Protein binding by agarose carrying hydrophobic groups in conjunction with charges

The binding of a series of proteins to agarose (Sepharose 4B) substituted with n-alkylamines of varying C-chain length (C₁, C₄ or C₈) has been investigated. At pH 8 and 0.05 ionic strength the negatively charged proteins (chymotrypsinogen X, serum albumin, ovalbumin and β-lactoglobulin), in constrast to the positively charged species (chymotrypsinogen A, α-chymotrypsin, and lysozyme) had strong affinity for the adsorbents with the longer C-chains (C₄, C₈). The binding appears to depend on cooperation between hydrophobic and electrostatic forces, the latter involving positive charges on the adsorbent which are introduced by the substitution process.