Synthesis and biological assays of peptides from a tuberculin-active protein.

The octapeptide Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly and the hexadecapeptide Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly-Lys-Asn-Gly-Ser-Gln-Met-Arg-Leu, part of a tuberculin-active intracellular mycobacterial protein, were synthesized. The synthetic peptides were shown to possess tuberculin activity by their ability to elicit a delayed-type allergic reaction in skin tests on Mycobacterium tuberculosis-sensitized guinea pigs. Purified protein derivative, the complex mixture of proteins of unknown composition which are excreted into the culture medium by M. tuberculosis and which is in wide use as a tuberculin-active preparation, was shown to cross-react weakly in the radioimmunoassays with the synthetic octapeptide when the 125I-labeled octapeptide and an anti-octapeptide antiserum were used.