Identification and characterization of the Sda beta 1,4,N-acetylgalactosaminyltransferase from pig large intestine.

The high occurrence in large intestine epithelial cells from pig of a beta-N-acetylgalactosaminyltransferase with a substrate specificity very similar to that of the Sda beta 1,4-N-acetylgalactosaminyltransferase from other tissues is reported. The enzyme strictly recognized the NeuAc alpha 2,3Gal beta terminal sequence of N- and O-linked oligosaccharides bound to glycoproteins. The transferase activity required Mn2+ and an optimum pH of 7.4. In contrast to the kidney Sda-enzyme from humans and other mammals, the microsomal fraction of pig colonic cells expressed a very high activity even in the absence of Triton X-100. A rapid procedure is presented for the large scale preparation of GalNAc beta 1,4(NeuAc alpha 2,3)Gal beta 1,4Glc from NeuAc alpha 2,3Gal beta 1,4Glc. The biosynthesized tetrasaccharide was completely resistant to the action of neuraminidase from Vibrio cholerae, whereas about 60% of N-acetylneuramic acid was cleaved by neuraminidase from Newcastle disease virus. HPLC separation of different compounds is reported.