The characterization of a UDP-N-acetylglucosamine: Gal beta 1-4Glc(NAc) beta 1-3 N-acetylglucosaminyltransferase in fluids from rat rete testis.
Using Gal beta 1-4GlcNAc or Gal beta 1-4Glc as substrates, the UDP-N-acetylglucosamine: Gal beta 1-4Glc(NAc) beta 1-3-N-acetylglucosaminyltransferase (GlcNAcTase) activity of rat rete testicular fluid was investigated with respect to the effects of pH and of divalent metal ions, apparent Km value, acceptor specificity and identity of products. The enzyme, whose activity was dependent absolutely on the presence of Mn2+, had an optimum pH of 7.5. It was completely inhibited by EDTA, Zn2+ and gossypol, and partially by Co2+ and Ca2+. Triton X-100 (1%) had no effect. When several oligosaccharides were tested as acceptors, the highest affinity was found with Gal beta 1-3[Gal beta 1-4GlcNAc beta 1-6]Gal beta 1-4Glc. With Gal beta 1-4Glc as acceptor, the product was identified from its 1H-NMR spectrum as GlcNAc beta 1-3Gal beta 1-4Glc (lacto-N-triose II) by reference to the spectrum of authentic lacto-N-triose II. Both testicular and epididymal fluids showed GlcNAcTase activity. In epididymis the specific activity increased gradually from the proximal caput to the proximal cauda.
Tsuji
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Y
Department of Bioresource Chemistry, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
Urashima
T
T
Matsuzawa
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T
D000818:Animals; D001826:Body Fluids / Q000201:enzymology; D002240:Carbohydrate Sequence; D007785:Lactose / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013737:Testis / Q000201:enzymology*; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000378:metabolism*
D014537:Uridine Diphosphate N-Acetylglucosamine; D017351:N-Acetylglucosaminyltransferases; D007785:Lactose