Isolation and Characterization of M-1 and M-2 Glycoproteins from Bovine, Porcine, and Avian Plasmas

Bovine, porcine, and avian M-1 and bovine and porcine M-2 glycoproteins were isolated from blood plasmas by ammonium sulfate fractionation and chromatography on carboxymethyl cellulose columns. The glycoproteins were homogeneous when subjected to starch gel and acrylamide gel electrophoresis with a number of buffers from pH 4.5 to pH 8.7. When subjected to horizontal starch gel or horizontal acrylamide gel electrophoresis at pH 2.68, the procine and avian M-1 glycoproteins did not exhibit polymorphism, whereas the bovine M-1 glycoprotein was resolved into two zones in the starch gel and into four zones in the acrylamide gel electrophoresis. The sedimentation coefficients, s020,w, of the bovine, porcine, and avian M-1 glycoproteins were 2.8, 3.0, and 2.9, respectively. The molecular weights of the bovine, porcine, and avian M-1 glycoproteins and of the bovine and porcine M-2 glycoproteins were 42,000, 47,000, 44,000, 55,000, and 54,000, respectively. The glycoproteins were analyzed for hexosamine, hexose, sialic acid, fucose, amino acids, and nitrogen. The porcine M-1 and M-2 glycoproteins contained 25.3% and 14.8% fucose, respectively, while the bovine and avian glycoproteins contained less than 1% fucose. The amino acid composition of avian M-1 glycoprotein was especially different from the bovine and porcine M-1 glycoproteins in lysine, aspartic acid, isoleucine, tyrosine, and histidine contents. The bovine and porcine M-1 glycoproteins differed in their contents of arginine, threonine, serine, cystine, valine, leucine, and phenylalanine, whereas the M-2 glycoproteins differed in their contents of aspartic acid, threonine, glutamic acid, proline, cystine, valine, and leucine.