These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Biosynthesis in vitro of core lacto-series glycosphingolipids by N-acetyl-D-glucosaminyltransferases from human colon carcinoma cells, Colo 205.
    Author: Basu M, Khan FA, Das KK, Zhang BJ.
    Journal: Carbohydr Res; 1991 Jan 15; 209():261-77. PubMed ID: 1828006.
    Abstract:
    Two N-acetyl-D-glucosaminyltransferases have been detected in human colon carcinoma Colo 205 cells. These enzymes catalyze the biosynthesis in vitro of the core-glycolipid of Type 1 and Type 2 lacto-series antigens and of the polylactosamine-containing longer chain antigenic structures, respectively. The first enzyme, GlcNAcT-1, which catalyzes the formation of lactotriosylceramide [LcOse3Cer, beta-D-GlcpNAc-(1----3)-LcOse2Cer, the core for all lacto-series Type 1 and Type 2 chains] from lactosylceramide [beta-D-Galp-(1----4)-D-Glcp-Cer, LcOse2Cer] and UDP-GlcNAc shows optimum activity in the presence of nonionic detergent Triton CF-54. The other enzyme, GlcNAcT-2, which catalyzes the biosynthesis in vitro of iLcOse5Cer [beta-D-GlcpNAc-(1----3)-nLcOse4Cer, the core for polylactosamine-containing antigens] from nLcOse4Cer [beta-D-Galp-(1----4)-LcOse3Cer] and UDP-GlcNAc, is optimally active with the zwitterionic detergent, Zwittergent 3-14, when membrane-bound. Both of these activities, however, can be extracted from the membrane by use of a nonionic detergent. Triton X-114, with nearly the same efficiency. These two transferases showed different pH optima, different cation and anion effects, and differential heat-inactivation patterns at 55 degrees. Permethylation studies of the radioactive products isolated from both of the enzyme-catalyzed reactions using respective 3H-substrates and nonradioactive UDP-GlcNAc showed the presence of 2,4,6-tri-O-methylgalactose in the hydrolyzed products. This indicated the presence of a (1----3)-linked beta-D-GlcpNAc group at the nonreducing end in both cases. The linkage of the beta-D-GlcpNAc group to the subterminal D-Gal residue in the two products was confirmed by an almost 90% cleavage of the terminal [3H]GlcNAc group by purified clam and papaya beta-D-hexosaminidases.
    [Abstract] [Full Text] [Related] [New Search]