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Proteolytic release of antigenic fragments corresponding to normal fecal antigen and non‐specific cross‐reacting antigen from carcinoembryonic antigen
Author(s) -
Matsuoka Y.,
Koga Y.,
Maruta H.,
Yoshino M.,
Tsuru E.
Publication year - 1978
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910210510
Subject(s) - carcinoembryonic antigen , antigen , pronase , radioimmunoassay , pepsin , immunodiffusion , proteolytic enzymes , chemistry , microbiology and biotechnology , peptide , biochemistry , biology , enzyme , cancer , immunology , trypsin , genetics
Abstract Three immunogenic parts have so far been identified in the carcinoembryonic antigen (CEA) molecule. These are: determinants cross‐reacting with the normal fecal antigen (NFA) (NFA determinant); determinants cross‐reacting with the non‐specific cross‐reacting antigen (NCA) (NCA determinant); and determinants which appear to be more cancer‐specific (cancer determinant). The chemical nature of these parts of the CEA molecule was investigated by digestion with proteolytic enzymes together with anti‐CEA preparations with which these three immunogenic parts of CEA molecule could be identified. The CEA digest obtained with pepsin did not react in immunodiffusion and radioimmunoassay, indicating that pepsin completely destroyed all the antigenic parts. Digestion by pronase E destroyed only the cancer determinant and liberated two antigenic fragments corresponding to the NFA determinant and the NCA determinant, respectively. These results suggest that the cancer determinant may reside in a protein or a peptide part of the molecule. The chemical nature of the NFA and NCA determinant remains to be clarified.