Chloroperoxidase (CPO) is a versatile fungal heme-thiolate protein that catalyzes a variety of one electron and two-electron oxidations. Chloroperoxidase is a versatile fungal heme-thiolate protein that catalyzes a variety of oxidations. CPO enzyme contains thirteen sugars, including five N-acetyl D-glucosamines (NAG) and eight mannoses (MAN), which are attached to the protein via the glycosidic bonds. Removal of the sugars from CPO leads to increase the hydrophobicity of the enzyme, as well as the reduction of the alkylation reactions. However, due to the lack of the proper force field for the sugars, they are ignored in the theoretical studies. The present study aims to assess the effects of the sugar segments on the structure and activity of CPO through the simulation of the halo structure and the structures without the sugar segment. Despite the difficulty of the process and being time-consuming, the suitable force field is introduced successfully for the sugars. According to molecular dynamics simulation (MD), seven channels and fifteen cavities are identified in the CPO structure. Two of the channels provide the substrate access to the active site. The MD simulation results reveal that the removal of NAG decreases the number of the cavities from fifteen to eleven. Besides, the removal of NAG is associated with removing the channel providing the substrate access. The number of the cavities decreases from fifteen to fourteen through the removal of MAN; however, channel providing the substrate access to the active site is partly preserved. The MD simulation results indicate that the structures without the sugar units are more compact in comparison with the halo structures. The removal of the sugar segments induces the significant changes in the flexibility of the residues that affect the catalytic activity of the enzyme. As a result, the enzyme activities, such as the oxidation, alkylation, halogenation, and epoxidation cannot occur when the sugar segments of the enzyme are removed.

氯过氧化物酶 (CPO) 是一种多功能的真菌血红素硫醇盐蛋白，可催化多种单电子和双电子氧化。氯过氧化物酶是一种多功能的真菌血红素硫醇盐蛋白，可催化多种氧化反应。CPO 酶含有 13 种糖，包括 5 种 N-乙酰 D-葡糖胺 (NAG) 和 8 种甘露糖 (MAN)，它们通过糖苷键与蛋白质相连。从 CPO 中去除糖会导致酶的疏水性增加，以及烷基化反应的减少。然而，由于糖缺乏合适的力场，在理论研究中它们被忽略了。本研究旨在通过模拟晕结构和不含糖链段的结构来评估糖链段对 CPO 结构和活性的影响。尽管该过程困难且耗时，但成功地为糖引入了合适的力场。根据分子动力学模拟 (MD)，在 CPO 结构中识别出 7 个通道和 15 个空腔。其中两个通道提供通往活性位点的底物通道。MD 模拟结果表明，NAG 的去除使空腔的数量从 15 个减少到 11 个。此外，NAG 的去除与去除提供衬底通道的通道相关。通过去除 MAN，腔数从 15 个减少到 14 个；但是，部分保留了提供通往活性位点的底物通道的通道。MD模拟结果表明，与晕结构相比，没有糖单元的结构更紧凑。糖片段的去除导致残基的灵活性发生显着变化，从而影响酶的催化活性。因此，当酶的糖段被去除时，酶的活性，如氧化、烷基化、卤化和环氧化作用就不会发生。