Comparison between the structures of NpAS and DgAS.

aThe distance and the angle cutoffs used for the calculation of H-bonds are 3.0 Å and 150°, respectively. The first number of the content in the bracket is the count of backbone-backbone H-bonds, the second one gives the count for the sidechain-sidechain/backbone H-bonds.bThe distance cutoff used for the calculation of salt bridges is 3.5 Å.a. 用于计算氢键（Hydrogen bonds）的截断距离与截断角度阈值分别为3.0 Å与150°。括号内内容的第一项为骨架-骨架氢键的计数，第二项则为侧链-侧链及侧链-骨架氢键的计数。 b. 用于计算盐桥（salt bridges）的截断距离阈值为3.5 Å。