An Unusual Papain Fragment Containing the VH Region of an IgG3 Myeloma Protein

[摘要] A new enzymatic fragment resulting from papain digestion of an IgG3 k myeloma cryoglobulin (protein KUP) is described. This fragment, which can be easily separated from the remainder of the Fab fragment by filtration on Sephadex G-100 in 1 N acetic acid, does not react with a panel of antisera in double diffusion experiments, has a blocked amino-terminal residue and was shown to correspond to most of the heavy chain variable region. It has been tentatively designated Fdv.Fdv is readily soluble in acidic buffers, has a molecular weight of 11,900, a sedimentation coefficient of 1.7S in 1 N acetic acid and contains about 100 residues.Attempts to isolate, under the same conditions, an analogous fragment from two additional IgG3 and one IgG1 myeloma proteins and from pooled human Cohn FII were unsuccessful. Whether production of Fdv is a unique property of protein KUP or is related to an unusual VH subgroup or other factors, remains, so far, undetermined.

[学科分类] 生物科学（综合）