Combinations of modified serum γ-globulin with other proteins

Abstract

Addition of serum γ-globulin exposed to high concentrations of guanidine hydrochloride for several hours to certain proteins results in formation of insoluble and soluble combinations of the modified serum γ-globulin with the other proteins. These combinations are formed under conditions where only the γ-globulin has been denatured. Effects of various experimental conditions on the formation of combinations have been evaluated. Egg albumin, serum albumin, and casein show a much smaller tendency to form combinations under comparable conditions than does γ-globulin. Combinations are readily obtained between modified γ-globulin and casein or native γ-globulin, but not between modified γ-globulin and serum albumin, egg albumin, or urease. Coupling of serum albumin or casein with diazotized sulfanilic acid or aniline markedly increases the extent of combination with the modified γ-globulin. At least two types of combinations are formed between the modified serum γ-globulin and serum albumin coupled with p-diazobenzenesulfonic acid. The insoluble combinations consist essentially of a matrix of γ-globulin from which the bulk of the combined azoalbumin can be extracted with alkyl or aryl sulfonates. The soluble combinations formed between modified γ-globulin and azoalbumin as well as some of the azoalbumin in the insoluble combinations cannot be dissociated under much more drastic conditions as evaluated by electrophoretic analyses. In electrophoresis the soluble combinations migrate as a single peak with mobility intermediate between the azoprotein and native γ-globulin.