抄録
A homologue of J-chain was purified from chicken serum IgM by ion-exchange chromatography on DEAE-cellulose followed by gel-filtration. Purified chicken J-chain showed a similar molecular weight to human J-chain and its molecular weight was calculated to be 19, 000 daltons.
The amino acid composition of chicken J-chain was also determined and a striking similarity in the content of systeine was found between J-chain of chicken and mammals. However, marked differences in amino acid composition of chicken J-chain were also observed in the contents of glutamic acid, asparatic acid, isoleucine, glycine, leucine and phenylalanine, when compared with those of mammalian J-chains. In spite of such differences in amino acid composition between J-chain of chickens and mammals, a precipitative cross-reaction between J-chain of chickens and human was observed with the antiserum to human J-chain, when reaction was proceeded in agarose gel incorporated with polyethylene glycol (Precipiplex).
NH2-terminal amino acid could not be detected in the dansylated J-chain, possibly indicating the blocked terminus similar to the human counterpart.
A component which was different from the J-chain in respects of its antigenicity and molecular weight (30, 000 daltons) but which had an electrophoretic mobility similar to J-chain on alkaline-urea-PAGE was identified in the chicken IgM. It was associated with the IgM by disulfide linkage and could possibly be confused with the chicken J-chain.
