Open AccessA Comparison of the Antigenic Specificity of Random and Ordered Linear Polypeptides Composed of l ‐Tyrosine, l ‐Alanine and l ‐Glutamic Acid
Author(s) -
Conwayjacobs Abigail,
Schechter Bilha,
Sela Michael
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01397.x
Subject(s) - tyrosine , chemistry , glutamic acid , alanine , pronase , biochemistry , stereochemistry , amino acid , precipitin , antibody , biology , enzyme , trypsin , immunology
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.