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A Comparison of the Antigenic Specificity of Random and Ordered Linear Polypeptides Composed of l ‐Tyrosine, l ‐Alanine and l ‐Glutamic Acid

1971; Wiley; Volume: 20; Issue: 3 Linguagem: Inglês

10.1111/j.1432-1033.1971.tb01397.x

1432-1033

Abigail Conway‐jacobs, Bilha Schechter, Michael Sela,

Protein purification and stability

Antibodies were provoked against a random copolymer of l ‐tyrosine, l ‐alanine, and l ‐glutamic acid, denoted as(Tyr,Ala,Glu) n , and against the α‐helical high molecular weight polymer containing the repeating sequence l ‐tyrosyl‐ l ‐alanyl‐ l ‐glutamyl, denoted as (Tyr‐Ala‐Glu) n . Significant crossreactions were found between anti‐(Tyr‐Ala‐Glu) n antibodies and (Tyr,Ala,Glu) n , as well as between anti‐(Tyr,Ala,Glu) n antibodies and (Tyr‐Ala‐Glu) n . Small peptides, obtained from a 45‐min pronase digestion of (Try,Ala,Glu) n efficiently inhibited precipitin reactions between anti‐(Tyr,Ala,Glu) n and (Tyr,Ala,Glu) n , anti‐(Tyr,Ala,Glu) n and (Tyr‐Ala‐Glu) n , and anti‐(Tyr‐Ala‐Glu) n and (Tyr,Ala,Glu) n . The peptides did not affect at all the reaction between anti‐(Tyr‐Ala‐Glu) n and (Try‐Ala‐Glu) n . It was concluded that the cross‐reaction between the (Tyr‐Ala‐Glu) n and (Tyr,Ala,Glu) n systems were due to sequential determinants in (Tyr‐Ala‐Glu) n rather than helix‐dependent determinants in (Tyr,Ala,Glu) n . The cross‐reactive fraction from anti‐(Tyr‐Ala‐Glu) n sera was isolated on a (Tyr,Ala,Glu) n immunoadsorbent and the purified antibodies were found to precipitate to a much larger extent with (Tyr,Ala,Glu) n than with (Tyr‐Ala‐Glu) n . These antibodies were probably produced against some degradation products of (Tyr‐Ala‐Glu) n produced in vivo.