Lomako J, Lomako W M, Whelan W J, Marchase R B
Department of Biochemistry and Molecular Biology, University of Miami, FL 33101.
FEBS Lett. 1993 Aug 30;329(3):263-7. doi: 10.1016/0014-5793(93)80234-l.
Rabbit-muscle glycogen contains covalently bound phosphorus, equivalent to 1 phosphate group per 208 glucose residues. This often disputed, minor component was previously thought to represent a phosphomonoester group at C-6 of a glucose residue. Here we show that more than half the phosphorus is present as a phosphodiester, the remainder being monoester. A novel enzyme activity has been found in muscle that can account for the presence of the phosphodiester in glycogen. This is a UDPglucose: glycogen glucose 1-phosphotransferase that positions glucose 1-phosphate on C-6 of glucose residues in glycogen, forming a diester. The phosphomonoester groups present may arise by removal of the glucose residue originally transferred as glucose 1-phosphate.
兔肌肉糖原含有共价结合的磷，相当于每208个葡萄糖残基有1个磷酸基团。这个一直存在争议的次要成分以前被认为是葡萄糖残基C-6位的磷酸单酯基团。我们在此表明，超过一半的磷以磷酸二酯形式存在，其余为单酯。在肌肉中发现了一种新的酶活性，它可以解释糖原中磷酸二酯的存在。这是一种UDP葡萄糖：糖原葡萄糖1-磷酸转移酶，它将葡萄糖1-磷酸定位在糖原中葡萄糖残基的C-6位，形成二酯。所存在的磷酸单酯基团可能是由于最初作为葡萄糖1-磷酸转移的葡萄糖残基被去除而产生的。
