A new kind of “thiophilic” electron‐donor‐acceptor adsorbent

Four simple agarose derivatives have been synthesized: 3‐(Z‐pyridylsulfido)‐2‐hydroxypropyl‐ 3‐(2‐pyridyloxy)‐2‐hydroxypropyl‐ 3‐(phenylsulfido)‐2‐hydroxypropyl‐, and 3‐(phenyloxy)‐2‐hydroxypropylagarose. Their affinities for serum proteins have been studied in the presence and absence of water‐structuring salt. About 50% of the proteins, among them immunoglobulins and α 2 ‐macroglobulin, but not albumin, were non‐covalently adsorbed to the PyS‐gel in buffer containing 0.5 M K 2 SO 4 . These proteins are the same as those adsorbed to the so‐called thiophilic gel, T‐gel (5), but there are some additional proteins found in the adsorbate that strongly indicate a specific influence on the protein adsorption exerted by the π‐electron system of the pyridine residue. The thio‐ether sulfur appears to be a necessary structural requirement for the characteristic adsorption behaviour. Thiophilic vs. hydrophobic ligand‐protein interaction is discussed.