Mechanism of binding of mouse interferon to controlled pore glass

Many proteins bind to controlled pore glass; they are either acid elutable or alkali elutable. Mouse interferon is an acid-elutable protein. Since poly(L-lysine) and, to some extent, poly(L-arginine) are also eluted from controlled pore glass under acidic conditions, one may postulate that mouse interferon binds to controlled pore glass via some of the protein's epsilon-amino groups (of lysine) and/or guanidinium groups (of arginine) and the beads' silanol (hydroxyl groups). The necessity of lysine in the binding of interferon to controlled pore glass is further substantiated by the fact that citraconylated interferon does not bind to controlled pore glass. A requirement for Lewis acid-base interaction between the beads' B2O3 groups and the amide groups of arginine is unlikely in view of the results obtained with the alternative system, ZrOH, which, being devoid of B2O3, did bind interferon. Since a substantial amount of interferon could be eluted from controlled pore glass with ethylene glycol and high salt, one may assume that some hydrophobicity is involved in the binding of interferon to controlled pore glass.