Cao Thinh-Phat, Choi Jin Myung, Lee Sang-Jae, Lee Yong-Jik, Lee Sung-Keun, Jun Youngsoo, Lee Dong-Woo, Lee Sung Haeng
Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 375 Seo-suk dong, Gwangju 501-759, Republic of Korea.
School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
Acta Crystallogr F Struct Biol Commun. 2014 Jan;70(Pt 1):108-12. doi: 10.1107/S2053230X13033724. Epub 2013 Dec 24.
L-arabinose isomerase (AI), which catalyzes the isomerization of L-arabinose to L-ribulose, can also convert D-galactose to D-tagatose, a natural sugar replacer, which is of commercial interest in the food and healthcare industries. Intriguingly, mesophilic and thermophilic AIs showed different substrate preferences and metal requirements in catalysis and different thermostabilities. However, the catalytic mechanism of thermophilic AIs still remains unclear. Therefore, thermophilic Geobacillus kaustophilus AI (GKAI) was overexpressed, purified and crystallized, and a preliminary X-ray diffraction data set was obtained. Diffraction data were collected from a GKAI crystal to 2.70 Å resolution. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 224.12, b = 152.95, c = 91.28 Å, β = 103.61°. The asymmetric unit contained six molecules, with a calculated Matthews coefficient of 2.25 Å(3) Da(-1) and a solvent content of 45.39%. The three-dimensional structure determination of GKAI is currently in progress by molecular replacement and model building.
L-阿拉伯糖异构酶（AI）可催化L-阿拉伯糖异构化为L-核酮糖，它也能将D-半乳糖转化为D-塔格糖，一种天然的糖替代品，在食品和医疗保健行业具有商业价值。有趣的是，嗜温AI和嗜热AI在催化过程中表现出不同的底物偏好和金属需求，并且热稳定性也不同。然而，嗜热AI的催化机制仍不清楚。因此，对嗜热嗜碱栖热袍菌AI（GKAI）进行了过表达、纯化和结晶，并获得了初步的X射线衍射数据集。从GKAI晶体收集到分辨率为2.70 Å的衍射数据。该晶体属于单斜空间群C2，晶胞参数为a = 224.12、b = 152.95、c = 91.28 Å，β = 103.61°。不对称单元包含六个分子，计算得到的马修斯系数为2.25 Å(3) Da(-1)，溶剂含量为45.39%。目前正在通过分子置换和模型构建对GKAI进行三维结构测定。
