HIBM Research Group, Inc., Glycan Technologies, Inc., P.O. Box 17993, Irvine, CA 92623, USA.
Biomolecules. 2020 Nov 29;10(12):1613. doi: 10.3390/biom10121613.
In studies on the degradation of glycogen by rhGAA, a glycosylated protein core material was found which consists of about 5-6% of the total starting glycogen. There was an additional 25% of the glycogen unaccounted for based on glucose released. After incubation of glycogen with rhGAA until no more glucose was released, no other carbohydrate was detected on HPAEC-PAD. Several oligosaccharides are then detectable if the medium is first boiled in 0.1 N HCl or incubated with trypsin. It is present in serum either in an HCl extract or in a trypsin digest. The characteristics of the in vivo serum material are identical to the material in the in vitro incubation medium. One oligosaccharide cannot be further degraded by rhGAA, from the incubation medium as well as from serum co-elute on HPAEC-PAD. Several masked oligosaccharides in serum contain -inositol, -inositol, and sorbitol as the major carbohydrates. The presence of this glycosylated protein in serum is a fraction of glycogen that is degraded outside the lysosome and the cell. The glycosylated protein in the serum is not present in the serum of Pompe mice not on ERT, but it is present in the serum of Pompe disease patients who are on ERT, so it is a biomarker of GAA degradation of lysosomal glycogen.
在 rhGAA 降解糖原的研究中，发现了一种糖基化蛋白核心物质，它约占起始糖原总量的 5-6%。根据释放的葡萄糖计算，还有 25%的糖原无法解释。在用 rhGAA 孵育糖原直到不再释放葡萄糖后，如果先将培养基在 0.1N HCl 中煮沸或用胰蛋白酶孵育，就可以检测到其他 25%的碳水化合物。如果先将培养基在 0.1N HCl 中煮沸或用胰蛋白酶孵育，就可以检测到几种低聚糖。在血清中，无论是 HCl 提取物还是胰蛋白酶消化物中，都存在这种物质。体内血清物质的特征与体外孵育培养基中的物质相同。一种低聚糖不能被 rhGAA 进一步降解，无论是在孵育培养基中还是在血清中，都可以通过 HPAEC-PAD 洗脱出来。血清中的几种掩蔽低聚糖含有肌醇、肌醇和山梨醇等主要碳水化合物。这种糖基化蛋白存在于血清中，是溶酶体和细胞外降解的糖原的一部分。在未接受 ERT 的庞贝病小鼠的血清中不存在这种糖基化蛋白，但在接受 ERT 的庞贝病患者的血清中存在，因此它是溶酶体糖原 GAA 降解的生物标志物。
