Isolation of a V_HC_λ Fragment on Tryptic Digestion of Human IgD Myeloma Proteins

Abstract

The tryptic digestion pattern of IgD myeloma proteins is reported. The Fab_δ fragment is shown to be very susceptible to further degradation to yield a novel fragment composed of VH and Cλ domains which are still bound through the interchain disulphide bridge. Reduction results in a change in M.W. from ca. 26,000 to 13,000. The loss of Fd_δ isotypic determinants may be of importance to studies in which membrane bound IgD is detected or measured after release from the cell surface by enzyme digestion.