Nephritogenic glycoprotein. XIV. A simple isolation method of nephritogenoside

Normal rat renal cortex contains three renal disease-inducing substances, that is, nephritogenoside, FX1A and immunogenoside (a novel renal glycoprotein that has the biological activity to induce only active Heymann nephritis). When renal cortex homogenate was treated with a detergent, Triton X-100, nephritogenoside was not eluted in the supernatant in which massive doses of FX1A and immunogenoside were detected. Thus, we searched for nephritogenoside in the precipitate. The precipitate was solubilized with trypsin, and nephritogenoside was easily and effectively isolated through columns of DEAE-cellulose followed by Bio-Gel A-1.5 m. The purified sample thus obtained is only composed of nephritogenoside, and contains neither FX1A nor immunogenoside. The yield of purified nephritogenoside was 3.8 mg (starting from 150 rats), which is about 5-6 times the recovery of the previous methodology. This newly developed simple method may be useful for the isolation of purified nephritogenoside. The chemical and immunologic properties of the purified sample prepared by the new method corresponded well with those of the nephritogenoside which was obtained by the previous methodology after exhaustive digestions with three proteolytic enzymes from homologous renal cortex.