Alonso M D, Lagzdins E J, Lomako J, Lomako W M, Whelan W J
Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, FL 33101.
FEBS Lett. 1995 Feb 13;359(2-3):110-12. doi: 10.1016/0014-5793(95)00018-5.
Glycogenin, the autocatalytic, self-glucosylating primer for glycogen synthesis by glycogen synthase, is presumed, in vivo, to use UDP-glucose as the source of the glucose residues it adds to itself. When we tested its ability to utilize other nucleoside diphosphate glucoses, it emerged that purine nucleotides are not utilized but two pyrimidine nucleotides are used, in addition to UDP-glucose. These are CDP-glucose and TDP-glucose. CDP-glucose is utilized at 70% of the rate of UDP-glucose. While there is no evidence that CDP-glucose is a natural substrate for glycogenin, it has the advantage over UDP-glucose in that it can be used specifically to detect and assay glycogenin in the presence of glycogen synthase because CDP-glucose, unlike UDP-glucose, is not a substrate for the synthase.
糖原素是糖原合酶合成糖原的自催化、自我葡糖基化引物，在体内推测其利用尿苷二磷酸葡萄糖（UDP-葡萄糖）作为添加到自身的葡萄糖残基的来源。当我们测试它利用其他核苷二磷酸葡萄糖的能力时，发现嘌呤核苷酸不被利用，但除了UDP-葡萄糖外，还有两种嘧啶核苷酸被利用。它们是胞苷二磷酸葡萄糖（CDP-葡萄糖）和胸苷二磷酸葡萄糖（TDP-葡萄糖）。CDP-葡萄糖的利用速率为UDP-葡萄糖的70%。虽然没有证据表明CDP-葡萄糖是糖原素的天然底物，但它相对于UDP-葡萄糖具有优势，因为在糖原合酶存在的情况下，它可用于特异性检测和测定糖原素，因为与UDP-葡萄糖不同，CDP-葡萄糖不是合酶的底物。
