Betty P. Barton

Structural characterization of γ1-heavy chain disease protein BAZ: Heterogeneity of the constant region

Abstract γ 1 -heavy chain disease protein (HCD) BAZ has a molecular weight of 60,000 daltons and contains a substantial quantity of carbohydrate (14%) in comparison to normal γ-chains which is distributed as follows: sialic acid (5%), fucose (1.7%), hexoses (3.5%), glucosamine (1.7%), and galactosamine (2.0%). Dansylation of the protein indicates that it has a blocked N -terminal amino acid, whereas treatment of the protein with hydrazine liberates glycine as the C-terminal amino acid. Thus, both amino and carboxy terminal residues appeared to be homologous to normal γ-chains. The amino acid composition of the protein also shows a markedly lower half-cystine content in comparison to other γ 1 -chains, indicating that the protein lacks interchain disulfide bridges connecting the heavy chains due to a deletion encompassing the hinge region. Amino acid sequence analysis of the C-terminal octadecapeptide of protein BAZ demonstrated a previously unrecognized amino acid substitution in the constant region. It contains a substitution of glycine for alanine at position 431. This exchange may conceivably represent another allotypic variant of IgGl proteins.

Physicochemical and immunochemical properties of γ1 heavy chain disease protein baz

Abstract The physicochemical and antigenic properties of a γ1 heavy chain disease protein (γl HCD BAZ) are described. Protein BAZ is positive for the Glm(1) determinant and gives a reaction of identity with Fc fragment, whether derived from Cohn Fraction II or from an IgG1 myeloma protein. It also gives a reaction of complete identity with the γHCD proteins CRA and ZUC. The mol. wt of the native protein was determined from (1) sedimentation-diffusion, (2) sedimentation-viscosity, and (3) sedimentation-equilibrium measurements to be approx 60,000 daltons. The mol. wt of the unreduced protein in 6 M guanidine hydrochloride was found to be 30,000 daltons, which was identical to that of the reduced-alkylated form in 6 M guanidine. These results established that γ1 HCD BAZ is a noncovalently linked dimer and suggested the possibility of a missing hinge region.

Multiple myeloma associated with a 9S IgG paraprotein and carcinoma of the prostate

A case of multiple myeloma associated with a 9S IgG complex. kappa‐type light chains, and adenocarcinoma of the prostate is described. The relative amount of 9S globulin was independent of total protein concentration; it was the predominant M‐component in both highly diluted serum and also in whole serum. At low pH, it was dissociated to the 7S monomer. The presence of moderately high concentrations of the 9S species in the patients serum did not cause symptoms of the hyperviscosity syndrome. A review of the literature suggests that the association of myeloma with nonreticular neoplasms may occur more often than previously supposed.