Offen Wendy A, Viksoe-Nielsen Anders, Borchert Torben V, Wilson Keith S, Davies Gideon J
York Structural Biology Laboratory, Department of Chemistry, The University of York, York YO10 5DD, England.
Novozymes A/S, Krogshoejvej 36, 2880 Bagsvaerd, Denmark.
Acta Crystallogr F Struct Biol Commun. 2015 Jan 1;71(Pt 1):66-70. doi: 10.1107/S2053230X14026508.
The enzyme-catalysed degradation of starch is central to many industrial processes, including sugar manufacture and first-generation biofuels. Classical biotechnological platforms involve steam explosion of starch followed by the action of endo-acting glycoside hydrolases termed α-amylases and then exo-acting α-glucosidases (glucoamylases) to yield glucose, which is subsequently processed. A key enzymatic player in this pipeline is the `Termamyl' class of bacterial α-amylases and designed/evolved variants thereof. Here, the three-dimensional structure of one such Termamyl α-amylase variant based upon the parent Geobacillus stearothermophilus α-amylase is presented. The structure has been solved at 1.9 Å resolution, revealing the classical three-domain fold stabilized by Ca2+ and a Ca2+-Na+-Ca2+ triad. As expected, the structure is similar to the G. stearothermophilus α-amylase but with main-chain deviations of up to 3 Å in some regions, reflecting both the mutations and differing crystal-packing environments.
酶催化的淀粉降解对于许多工业过程至关重要，包括制糖和第一代生物燃料。传统生物技术平台包括淀粉的蒸汽爆破，随后是内切糖苷水解酶（称为α-淀粉酶）的作用，然后是外切α-葡萄糖苷酶（糖化酶）的作用以产生葡萄糖，随后对其进行加工。该流程中的一个关键酶是细菌α-淀粉酶的“嗜热栖热放线菌淀粉酶（Termamyl）”类别及其设计/进化变体。在此，展示了一种基于亲本嗜热栖热放线菌α-淀粉酶的此类嗜热栖热放线菌淀粉酶变体的三维结构。该结构已在1.9 Å分辨率下解析，揭示了由Ca2+和Ca2+-Na+-Ca2+三联体稳定的经典三结构域折叠。正如预期的那样，该结构与嗜热栖热放线菌α-淀粉酶相似，但在某些区域主链偏差高达3 Å，这反映了突变和不同的晶体堆积环境。
