Yoon H J, Hashimoto W, Miyake O, Murata K, Mikami B
Research Institute for Food Science, Kyoto University, Uji Kyoto 611-0011, Japan.
J Mol Biol. 2001 Mar 16;307(1):9-16. doi: 10.1006/jmbi.2000.4509.
The structure of A1-III from a Sphingomonas species A1 complexed with a trisaccharide product (4-deoxy-l-erythro-hex-4-enepyranosyluronate-mannuronate-mannuronic acid) was determined by X-ray crystallography at 2.0 A with an R-factor of 0.16. The final model of the complex form comprising 351 amino acid residues, 245 water molecules, one sulfate ion and one trisaccharide product exhibited a C(alpha) r.m.s.d. value of 0.154 A with the reported apo form of the enzyme. The trisaccharide was bound in the active cleft at subsites -3 approximately -1 from the non-reducing end by forming several hydrogen bonds and van der Waals interactions with protein atoms. The catalytic residue was estimated to be Tyr246, which existed between subsites -1 and +1 based on a mannuronic acid model oriented at subsite +1.
通过X射线晶体学在2.0埃分辨率下测定了来自鞘氨醇单胞菌属A1的A1-III与三糖产物（4-脱氧-L-赤藓糖基己-4-烯吡喃糖醛酸-甘露糖醛酸-甘露糖醛酸）复合物的结构，R因子为0.16。包含351个氨基酸残基、245个水分子、一个硫酸根离子和一个三糖产物的复合物最终模型与已报道的该酶无配体形式相比，Cα均方根偏差值为0.154埃。三糖通过与蛋白质原子形成多个氢键和范德华相互作用，结合在活性裂隙中从非还原端起的-3至-1亚位点处。基于位于+1亚位点的甘露糖醛酸模型，催化残基估计为Tyr246，其存在于-1和+1亚位点之间。
