Manzella S, Ananth S, Oegema T R, Rodén L, Rosenberg L C, Meezan E
Department of Pharmacology, School of Medicine, University of Alabama at Birmingham 35294, USA.
Arch Biochem Biophys. 1995 Jul 10;320(2):361-8. doi: 10.1016/0003-9861(95)90020-9.
The self-glucosylation of beef kidney glycogenin was inhibited by the following pyrimidine nucleotides and nucleotide sugars, listed in order of decreasing effectiveness: CDP-glucose, CDP, UDP-xylose, UDP-N-acetylglucosamine, UDP-galactose, UDP, CTP, CDP-choline, UDP-glucuronic acid, beta-S-UDP-glucose, and CMP. In contrast, the purine nucleotide sugars, ADP-glucose and GDP-glucose, were essentially ineffective, as was the pyrimidine nucleoside, cytidine. UDP-Xylose may be utilized by glycogenin as an alternative sugar donor instead of UDP-glucose (Rodén, L., Ananth, S., Campbell, P., Manzella, S., and Meezan, E. (1994) J. Biol. Chem. 269, 11509-11513) and therefore presumably inhibited the glucosyl transfer reaction by being a competitive substrate. Like glucosyl transfer, xylosyl incorporation into glycogenin was also inhibited effectively by CDP. On the other hand, UDP-xylose:proteoglycan core protein xylosyltransferase (EC 2.4.2.26) was not affected by CDP, nor was it inhibited by UDP-glucose. Addition of CDP or UDP-glucose to reaction mixtures containing both enzymes therefore made it possible to assay xylosyltransferase EC 2.4.2.26 reliably without the extensive product characterization that is otherwise necessary. The CDP effect on glycogenin further allowed the development of an improved procedure for the purification of this enzyme, in which specific elution of an affinity matrix (UDP-glucuronic acid-agarose) was carried out with CDP as the eluant.
牛肉肾糖原素的自糖基化作用受到以下嘧啶核苷酸和核苷酸糖的抑制，按抑制效果递减顺序排列如下：CDP-葡萄糖、CDP、UDP-木糖、UDP-N-乙酰葡糖胺、UDP-半乳糖、UDP、CTP、CDP-胆碱、UDP-葡糖醛酸、β-S-UDP-葡萄糖和CMP。相比之下，嘌呤核苷酸糖ADP-葡萄糖和GDP-葡萄糖基本无效，嘧啶核苷胞苷也是如此。UDP-木糖可被糖原素用作替代糖供体，替代UDP-葡萄糖（罗登，L.，阿南特，S.，坎贝尔，P.，曼泽拉，S.和米赞，E.（1994年）《生物化学杂志》269卷，11509 - 11513页），因此推测它作为竞争性底物抑制了糖基转移反应。与糖基转移一样，木糖掺入糖原素也受到CDP的有效抑制。另一方面，UDP-木糖：蛋白聚糖核心蛋白木糖基转移酶（EC 2.4.2.26）不受CDP影响，也不被UDP-葡萄糖抑制。因此，向含有这两种酶的反应混合物中添加CDP或UDP-葡萄糖，使得能够可靠地测定木糖基转移酶EC 2.4.2.26，而无需进行大量的产物鉴定，否则这是必要的。CDP对糖原素的作用进一步促成了一种改进的该酶纯化方法的开发，其中以CDP作为洗脱剂对亲和基质（UDP-葡糖醛酸-琼脂糖）进行特异性洗脱。
