Hosomi O, Takeya A, Kogure T
J Biochem. 1984 Jun;95(6):1655-9. doi: 10.1093/oxfordjournals.jbchem.a134778.
Human serum was shown to contain N-acetyllactosamine: N-acetylglucosaminyltransferase activity. The reaction product was hydrolyzed by beta-N-acetylglucosaminidase and released [14C]N-acetylglucosamine, indicating that the N-acetylglucosaminyl residue was beta-linked to N-acetyllactosamine. Methylation and hydrolysis of the reaction product yielded 2,4,6-trimethyl[3H]galactose, indicating that the N-acetylglucosaminyl residue was introduced at position C-3 of the terminal galactose of N-acetyllactosamine. In our experiments, 2,3,4-trimethyl[3H]galactose was not detected. Substrate competition studies between N-acetyllactosamine and lactose showed that this enzyme also catalyzed the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to lactose. Since the Km value for N-acetyllactosamine, which was 7.0 mM, was approximately a fourth of that for lactose (29.8 mM), N-acetyllactosamine was more effective than lactose as an acceptor.
人血清显示含有N-乙酰乳糖胺：N-乙酰葡糖胺基转移酶活性。反应产物被β-N-乙酰葡糖胺酶水解并释放出[14C]N-乙酰葡糖胺，这表明N-乙酰葡糖胺残基以β-连接方式连接到N-乙酰乳糖胺上。反应产物的甲基化和水解产生了2,4,6-三甲基[3H]半乳糖，这表明N-乙酰葡糖胺残基是在N-乙酰乳糖胺末端半乳糖的C-3位引入的。在我们的实验中，未检测到2,3,4-三甲基[3H]半乳糖。N-乙酰乳糖胺和乳糖之间的底物竞争研究表明，该酶也催化了N-乙酰葡糖胺从UDP-N-乙酰葡糖胺转移到乳糖上。由于N-乙酰乳糖胺的Km值为7.0 mM，约为乳糖（29.8 mM）的四分之一，因此N-乙酰乳糖胺作为受体比乳糖更有效。
