Investigation of the carrier function of polypeptides. Synthesis, conformation and cytotoxicity of oxazolone conjugates of poly(Lys) and poly[Lys‐(DL‐ALAm)]

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Abstract
A new group of synthetic macromolecular conjugates was synthesised in which poly(Lys) or a branched polypeptide poly[Lys‐(DL‐Alam)] (m≅3) were used as carrier and 4‐(ethoxymethylene)‐2–phenyl–5 (4H)‐oxazolone as hapten. These conjugates were characterized by amino acid analysis, identification of terminal residues of the side chain, sedimentation analysis. The conformation of conjugates and of carrier polypeptides were analyzed by circular dichroism spectroscopy in water solutions at various pH and ionic strengths. These data indicated a marked dependence of the conformation of the conjugate on the structure of carrier and on the number of the side chain terminal haptens (phOx). In vitro cytotoxicity of these polymers was also investigated using two different assays, by measuring the viability of isolated rat liver cells and the effect on growth of HeLa cells. Toxicity of polypeptides could be diminished by conjugates containing a higher amount of oxazolone. These conjugates with defined conformation and toxicological properties are considered suitable to analyse the carrier function of branched polypeptides, particularly the interaction with the immunological network.
Funding Information
  • Hungarian Academy of Sciences grants: OTKA (1-600-2-86-1-484, No. 841 and No. 1986/27-3-671)