52 human lambda immunoglobulin chains could be divided into two antigenic subtypes, St(+) and St (-).St( +) type chains represent a homogeneous structural group differing from St( -) type proteins by characteristic subclass specific positions in the N-terminal sequence of amino acids. St(+) proteins follow the "Ha" type sequence. St(+) type molecules are present in normal L-chain preparations. 19 of normal lambda chains appear to consist of St( +) type molecules.St(-) type chains include at least two isotypic variants, following the "Bo" and "X" type sequence of amino acids respectively. The results point in the direction that 3 germ-line genes, one st(+) and two st(-) genes, encode the specificity region of lambda polypeptide chains.No correlation between N-terminal St markers and the lysine-arginine interchange a t position 190 of the C-terminal half was found; thus evidence of the unigenic control of the lambda molecule was not provided. [6,7]. The correlation of these different markers was studied in 52 lambda Bence Jones proteins and isolated myeloma lambda chains. Furthermore, an attempt was made to correlate St specificity with the chemical structure of lambda chains.
MATERIALS AND METHODS
Bence Jones ProteinsLambda Bence Jones proteins of 50 patients with multiple myeloma, Waldenstrom-type macroglobulinemia and related plasma cell dyscrasias were studied. 42 Bence Jones proteins were isolated from urine by precipitation with 60°/, ammonium sulfate and further purified by chromatography on DEAE cellulose (phosphate buffer, pH 8.0, gradient and/or step-wise elution). They were found to be free of protein contaminants by immunoelectrophoresis and immunodiffusion tests using appropriate antisera.
Fractionation of yG-GlobulinI n two instances Bence Jones proteins and L-chains of the corresponding serum $3,-globulins were compared and in additional two instances lambda chains of yG, and yGl were studied. Partial reduction and alkylation of intact yG was performed by a modification of the method of Fleischman, Pain and Porter [8]. Heavy and light chains were separated a t 4" on a column packed with a mixture of Sephadex G-200 (2 parts by weight) and Sephadex G-100 (1 part) equilibrated with 0.1 M formic acid.
St Typing of Lambda ChainsI n a previous article [7] we have shown that St( +) determinants are "hidden" antigenic sites inaccessible in the intact yG-molecule. St( + ) specific antisera were prepared by absorption of rabbit antisera against lambda Bence Jones protein St (Oz -) with lyophilized normal serum or intact yG-globulin. I n the present experiments St(+) and St(-) proteins were distinguished by their ability to spur over intact yG-globulin. Lambda chains giving spurs over
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