Amino acid composition of the mu chains of IgM of normal serum, monoclonal cryoglobulin and Waldenstrom macroglobulin.

The purified IgM of normal human serum, monoclonal cryoglobulin and Waldenstrom macroglobulin were reduced, alkylated and subjected to Sephadex G-100 filtration. The mu chains separated were hydrolysed and analysed for amino acid content. In both monoclonal proteins the content of hydroxyproline in mu chains was lower than in the IgM of normal serum. The mu chain of monoclonal cryoglobulin contained less serine, methionine and tyrosine, whereas mu chains of Waldenstrom macroglobulin showed a lower level of cystine as compared with the IgM of normal serum. On the other hand, the content of valine and basic amino acids was higher in both monoclonal proteins.