Catalytic Reaction Mechanism of Bacterial GH92 α-1,2-Mannosidase: A QM/MM Metadynamics Study

The catalytic mechanism of a -dependent family 92 -mannosidase, which is abundantly present in human gut flora and malfunctions leading to the lysosomal storage disease α-mannosidosis, has been investigated using quantum mechanics/molecular mechanics and metadynamics methods. Computational efforts show that the enzyme follows a conformational itinerary of and the ion serves a dual purpose, as it not only distorts the sugar ring but also plays a crucial role in orchestrating the arrangement of catalytic residues. This orchestration, in turn, contributes to the facilitation of conformers for the ensuing reaction. This mechanistic insight is well-aligned with the experimental predictions of the catalytic pathway, and the computed energies are of the same order of magnitude as the experimental estimations. Hence, our results extend the mechanistic understanding of glycosidases.     

2,2,6,6-四甲基-4-哌啶酮对小白鼠血清α-甘露糖苷酶的影响

体外试验表明，2，2，6，6-四甲基-4-哌啶酮（TMPD）对小鼠血清α-甘露糖苷酶（AMA）活性（以水解对硝基苯基-α-D-甘露糖苷产生对硝基酚计）具有明显的抑制作用；体内试验用剂量为200、300和400mg/kgBW的TMPD给小鼠每日灌胃一次，分别于第1、2、5、10、20、30、35d采集血液，测定血清AMA活性，结果表明：这3个剂量的TMPD均显著地抑制该酶活性，随TMPD浓度的增加，抑制率相应增加，而灌胃次数增加，酶活性反而有不同程度回升，但不能恢复到初始水平。