Synthesis and characterization of a recombinant fragment of human α-fetoprotein with antigenic selectivity versus albumin

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Abstract
A DNA sequence coding for human α-fetoprotein amino acid sequence 38–119 was synthesized and cloned in a bacterial expression vector. The α-fetoprotein sequence was selected as the least homologous to albumin, since the two proteins have an overall amino acid identity of %. A chimeric protein was obtained which was purified by preparative electrophoresis and characterized in its primary structure by fast atom bombardment mass spectrometry. About 70% of the α-fetoprotein sequence was physically mapped and found to correspond to the amino acids encoded in the synthetic gene. The use of this recombinant protein allowed the selection of monoclonal antibodies recognizing both the recombinant fragment and native α-fetoprotein. These antibodies should allow the development of an immunoassay for α-fetoprotein with absolute selectivity versus albumin. This might result in more sensitive clinical determinations, avoiding the possibility of cross-reactions.