Schuman B, Fisher S Z, Kovalevsky A, Borisova S N, Palcic M M, Coates L, Langan P, Evans S V
Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 Feb 1;67(Pt 2):258-62. doi: 10.1107/S1744309110051298. Epub 2011 Jan 22.
The biosyntheses of oligosaccharides and glycoconjugates are conducted by glycosyltransferases. These extraordinarily diverse and widespread enzymes catalyze the formation of glycosidic bonds through the transfer of a monosaccharide from a donor molecule to an acceptor molecule, with the stereochemistry about the anomeric carbon being either inverted or retained. Human ABO(H) blood group A α-1,3-N-acetylgalactosaminyltransferase (GTA) generates the corresponding antigen by the transfer of N-acetylgalactosamine from UDP-GalNAc to the blood group H antigen. To understand better how specific active-site-residue protons and hydrogen-bonding patterns affect substrate recognition and catalysis, neutron diffraction studies were initiated at the Protein Crystallography Station (PCS) at Los Alamos Neutron Science Center (LANSCE). A large single crystal was subjected to H/D exchange prior to data collection and time-of-flight neutron diffraction data were collected to 2.5 Å resolution at the PCS to ∼85% overall completeness, with complementary X-ray diffraction data collected from a crystal from the same drop and extending to 1.85 Å resolution. Here, the first successful neutron data collection from a glycosyltransferase is reported.
寡糖和糖缀合物的生物合成由糖基转移酶进行。这些极其多样且广泛存在的酶通过将单糖从供体分子转移到受体分子来催化糖苷键的形成，异头碳周围的立体化学构型会发生翻转或保留。人类ABO(H)血型A α-1,3-N-乙酰半乳糖胺基转移酶（GTA）通过将N-乙酰半乳糖胺从UDP-GalNAc转移到血型H抗原上生成相应抗原。为了更好地理解特定活性位点残基质子和氢键模式如何影响底物识别和催化作用，在洛斯阿拉莫斯中子科学中心（LANSCE）的蛋白质晶体学站（PCS）开展了中子衍射研究。在数据收集之前，对一块大单晶进行了H/D交换，并在PCS收集了飞行时间中子衍射数据，分辨率达到2.5 Å，总体完整性约为85%，同时从同一液滴中的晶体收集了互补的X射线衍射数据，分辨率延伸至1.85 Å。在此，报道了首次从糖基转移酶成功收集到中子数据。
