Nephritogenic glycoprotein. VIII. Isolation and partial characterization of nephritogenic glycopeptide (nephritogenoside) from the terminal chorionic villus of human placenta

Abstract

A glycopeptide comparable to human renal nephritogenic glycopeptide (nephritogenoside) of glomerular basement membrane (GBM) origin was isolated and purified from human placenta. Trophoblast basement membranes (TrBM) were isolated from placental terminal villi by ultrasonic disruption, and digested with trypsin and then with pronase. TrBM were then fractionated by zone electrophoresis, concanavalin A (Con A) affinity column chromatography and Bio-Gel P200 column chromatography. From 250 g (wet weight) of human placental terminal villi, we obtained a purified sample of 0.7 mg (dry weight) of glycopeptide. Ouchterlony gel diffusion demonstrated the existence of a common precipitin line between purified human placental glycopeptide and antiserum against human renal nephritogenic glycopeptide prepared from GBM. The sugar composition of this glycopeptide was rich in glucose (glucose, galactose and mannose were in the ratio of 1.00:0.30:0.33) and the amino acid composition of this glycopeptide contained no collagenous components. These results indicate that at least one of the nephritogenic substances common to the placenta and kidney is a glycoprotein rich in glucose and different from the collagenous component of the basement membrane.