• 1 January 1979
    • journal article
    • research article
    • Vol. 360  (12) , 1919-1940
Abstract
Myeloma protein Tro was isolated from the plasma of a myeloma patient. Monomeric Ig[immunoglobulin]A was separated from its polymer (by chromatography on Sephadex G-200). Both forms were split with pepsin or cyanogen bromide and, if necessary, with thermolysin and subtilisin. The cystin-containing peptides were isolated from the hydrolysates by chromatography on Sephadex, ion-exchange columns, preparative paper chromatography, TLC, electrophoresis or by a combination of these methods. They were characterized by amino acid analyses and by determination of the N-terminal amino acids using the Dansyl-Edman procedure. All the disulfide bridges of an IgA 1 could be established. The monomer has all together 48 cysteines, 7 in each L- and 17 in each H-chain; all these are covalently bonded by SS-bridges. Free SH-groups were not detected. The J-chain could only be identified serologically in the polymeric form of the protein. The subunits of the polymers are covalently attached through Cys13, Cys17 or both these residues of the H-chain.

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