Thomsen Maren, Skalden Lilly, Palm Gottfried J, Höhne Matthias, Bornscheuer Uwe T, Hinrichs Winfried
Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Strasse 4, 17489 Greifswald, Germany.
Acta Crystallogr D Biol Crystallogr. 2014 Apr;70(Pt 4):1086-93. doi: 10.1107/S1399004714001084. Epub 2014 Mar 20.
The importance of amine transaminases for producing optically pure chiral precursors for pharmaceuticals and chemicals has substantially increased in recent years. The X-ray crystal structure of the (R)-selective amine transaminase from the fungus Aspergillus fumigatus was solved by S-SAD phasing to 1.84 Å resolution. The refined structure at 1.27 Å resolution provides detailed knowledge about the molecular basis of substrate recognition and conversion to facilitate protein-engineering approaches. The protein forms a homodimer and belongs to fold class IV of the pyridoxal-5'-phosphate-dependent enzymes. Both subunits contribute residues to form two active sites. The structure of the holoenzyme shows the catalytically important cofactor pyridoxal-5'-phosphate bound as an internal aldimine with the catalytically responsible amino-acid residue Lys179, as well as in its free form. A long N-terminal helix is an important feature for the stability of this fungal (R)-selective amine transaminase, but is missing in branched-chain amino-acid aminotransferases and D-amino-acid aminotransferases.
近年来，胺转氨酶在生产用于制药和化工的光学纯手性前体方面的重要性显著提高。通过单波长异常散射（S-SAD）相位法解析了烟曲霉（Aspergillus fumigatus）中（R）-选择性胺转氨酶的X射线晶体结构，分辨率达到1.84 Å。1.27 Å分辨率下的精修结构提供了关于底物识别和转化的分子基础的详细信息，以促进蛋白质工程方法的开展。该蛋白质形成同型二聚体，属于磷酸吡哆醛依赖性酶的折叠类IV。两个亚基均提供残基以形成两个活性位点。全酶结构显示，具有催化重要性的辅因子磷酸吡哆醛以内部醛亚胺的形式与起催化作用的氨基酸残基Lys179结合，同时也以游离形式存在。一个长的N端螺旋是这种真菌（R）-选择性胺转氨酶稳定性的一个重要特征，但在支链氨基酸转氨酶和D-氨基酸转氨酶中不存在。
