Specific Technique for the Isolation of Human α₂-Macroglobulin

Abstract

NORMAL human serum contains two kinds of macroglobulin, the _γ1M (or β₂M)-group and α₂-macroglobulin; the latter was first isolated and described by Schultze and co-workers¹. The macroglobulin isolated by Brown et al. from Cohn's Fraction III° seems to be the same protein². Although α₂-macroglobulin corresponds to about 3 per cent of total serum protein, its biological significance is still unknown. This may be a sufficient explanation for the rather scarce literature concerning it. However, it seems to us that the main reason might be the difficulty of obtaining this protein in a pure state and in sufficient quantity. This involves a complete fractionation scheme^1,2, or the use of small-scale techniques involving ultracentrifugation or preparative electrophoresis^3–5. A specific and simple isolation technique is still lacking.