Department of Chemistry, Division of Advanced Materials Science, Polymer Research Institute, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
Department of Microbiology, Dongguk Medical Institute, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea.
Int J Biol Macromol. 2019 Apr 15;127:286-296. doi: 10.1016/j.ijbiomac.2019.01.053. Epub 2019 Jan 14.
Bacillus licheniformis α-amylase (BLA) in a biomimetic buffer and extrinsic solutions (various pH values, temperatures, and metal ions) has been investigated for the first time in the view of three-dimensional (3D) structure by synchrotron X-ray and dynamic light scattering analyses. BLA in buffer is determined to have a structure resembling its crystallographic structure; but the 3D structure is slightly larger than the crystal structure. Such a structure is maintained with little variations in extrinsic solutions of pH 4.0-9.7, temperature 4-55 °C, and metal ions such as Ba, Mg, and Li. These results collectively inform that BLA tends to favorably form a stable monomeric structure, which could provide structural clues to its enzymatic activities in moderate levels. Interestingly, BLA is found to reveal highly expanded structures at 65-75 °C and in Co solution, which could correlate to the significantly pronounced enzymatic activities. However, BLA shows somewhat shrunken structures at pH 3.0 and in Hg solution, supporting for the suppressed activities under these conditions.
首次通过同步加速器 X 射线和动态光散射分析，从三维（3D）结构的角度研究了生物模拟缓冲液和外液（各种 pH 值、温度和金属离子）中的地衣芽孢杆菌α-淀粉酶（BLA）。在缓冲液中，BLA 被确定具有类似于其晶体结构的结构；但 3D 结构比晶体结构略大。在 pH 值为 4.0-9.7、温度为 4-55°C 以及钡、镁和锂等金属离子的外液中，这种结构保持不变。这些结果共同表明，BLA 倾向于形成稳定的单体结构，这为其在中等水平下的酶活性提供了结构线索。有趣的是，BLA 在 65-75°C 和 Co 溶液中表现出高度扩展的结构，这可能与显著增强的酶活性有关。然而，BLA 在 pH 值为 3.0 和 Hg 溶液中显示出略微收缩的结构，这支持了在这些条件下活性受到抑制的情况。
