Department of Bioinformatics, School of Medical Informatics , Xuzhou Medical University , Xuzhou 221000 , Jiangsu Province , China.
Jiangsu Provincial Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy , Xuzhou Medical University , Xuzhou 221000 , Jiangsu Province , China.
Biomacromolecules. 2019 Jul 8;20(7):2821-2829. doi: 10.1021/acs.biomac.9b00586. Epub 2019 Jun 18.
Glycogen, a randomly branched glucose polymer, provides energy storage in organisms. It forms small β particles which in animals bind to form composite α particles, which give better glucose release. Simulations imply β particle size is controlled only by activities and sizes of glycogen biosynthetic enzymes and sizes of polymer chains. Thus, storing more glucose requires forming more β particles, which are expected to sometimes form α particles. No α particles have been reported in bacteria, but the extraction techniques might have caused degradation. Using milder glycogen extraction techniques on Escherichia coli, transmission electron microscopy and size-exclusion chromatography showed α particles, consistent with this hypothesis for α-particle formation. Molecular density and size distributions show similarities with animal glycogen, despite very different metabolic processes. These general polymer constraints are such that any organism which needs to store and then release glucose will have similar α and β particle structures: a type of convergent evolution.
糖原是一种随机分支的葡萄糖聚合物，为生物体提供能量储存。它形成小的β颗粒，在动物中结合形成复合的α颗粒，从而更好地释放葡萄糖。模拟表明，β颗粒的大小仅受糖原生物合成酶的活性和大小以及聚合物链的大小控制。因此，储存更多的葡萄糖需要形成更多的β颗粒，而这些β颗粒有时会形成α颗粒。细菌中尚未报道有α颗粒，但提取技术可能导致了降解。使用更温和的糖原提取技术对大肠杆菌进行研究，透射电子显微镜和排阻色谱分析显示了α颗粒，这与α颗粒形成的假设一致。尽管代谢过程非常不同，但分子密度和大小分布与动物糖原相似。这些普遍的聚合物限制使得任何需要储存和释放葡萄糖的生物体都具有相似的α和β颗粒结构：这是一种趋同进化。
