Partial sequence determination of normal pooled human immunoglobulin M

A rapid procedure for the isolation of human IgM myeloma proteins

A two-step rapid procedure for the isolation of human IgM paraproteins from plasma samples is described. It involves gel filtration on Ultrogel AcA 34 followed by anion exchange chromatography on DEAE-Sepharose CL6B. The overall yield of IgM is greater than 70% and the final product is pure as judged by immunoelectrophoresis and SDS-polyacrylamide gel electrophoresis. The procedure is applicable to both euglobulin and cryoglobulin IgM proteins of a wide range of electrophoretic mobilities.

The primary structure of the constant part of mu-chain-disease protein BOT

The complete primary structure of the constant part of the mu-chain-disease protein, BOT, was established. It includes the whole CH2, CH3 and CH4 domains. two amino acid changes were found, at positions 309 (Ser leads to Gly) and 333 (Val leads to Gly) (GAL numbering). In two additional monoclonal mu chains (SCO and CO), the same positions showed an amino acid variability. From these data it may be concluded that four types of mu chains exist in the human: (1) GAL type with Ser-309 and Val-333; (2) OU type with Gly-309 and Val-333; (3) SCO type with Ser-309 and Gly-333; (4) BOT/CO type with Gly-309 and Gly-333. The meaning of this molecular polymorphism is discussed.