Abstract
Similarities and dissimilarities of amino acid sequences among the acidic subunits were analyzed by quantitative immunological precipitin with antibodies to the subunits, gel filtration of the CNBr-fragments and ion exchange chromatography of the tryptic peptides.
The gel chromatograms of the CNBr-fragments and the ion exchange chromatograms of the tryptic peptides of A1 and A2 subunits have demonstrated that they are two distinct polypeptide subunits which have very similar primary structures. Quantitative immunological precipitin revealed that A1, A2 and A3 subunits were strongly immunologically related, therefore indicated that they shared a considerable degree of sequence homology. In fact, the analyses of the tryptic peptides of A1, A2 and A3 subunits showed the sequence homology among the three subunits. Although A4 subunit was shown to be serologically distinct polypeptide subunits from the other three subunits, some similarities of amino acid sequences were observed by the analyses of the tryptic peptides.
