A glycoprotein of high molecular weight in the urine of germ-free rats.

A carbohydrate-rich glycoprotein fraction was obtained by purification of the non-dialysable material of germ-free rat urine. This procedure involved proteolytic digestion with pronase, presipitation of the acidic glycoprotein with cetyltrimethyl-ammonium bromide (CTAB), and chromatography on DEAE-Sephadex and finally on Sepharose 4B from which it was partly excluded. The purified glycoprotein contained fucose (10.1%), galactose (12.2%).N-acetylglucosamine (16.6%), N-acetylgalactosamine (19.8%), sialic acid (11.9%), and sulphate ester groups (0.7%). The amino acid content was 19%, threonine, serine and proline being the predominating amino acids. Gel electrophoresis and gel chromatography revealed a pronounced poly-dispersity of the material. Treatment of the glycoprotein with alkali in the presence of borohydride led to partial degradation of the polymer with the formation of fragments containing N-acetylgalactosaminitol. The chemical properties of the purified glycoprotein are characteristic of a mucin. The presence of this glycoprotein could not be demonstrated in conventional rat urine.