Lumb K J, Aplin R T, Radford S E, Archer D B, Jeenes D J, Lambert N, MacKenzie D A, Dobson C M, Lowe G
Inorganic Chemistry Laboratory, University of Oxford, UK.
FEBS Lett. 1992 Jan 20;296(2):153-7. doi: 10.1016/0014-5793(92)80368-q.
The production of a mutant hen lysozyme is described in which Asp-52, one of the catalytically important residues, is replaced by Ser. The mutant enzyme has very low catalytic activity but NMR studies show that its structure is closely similar to that of the wild-type protein. NMR experiments also show that well defined complexes are formed with GlcNAc4 and GlcNAc6 bound in the active site of the mutant enzyme. These complexes have been examined using electrospray mass spectrometry (ESMS). The most intense peaks arise from the uncomplexed protein indicating that dissociation takes place in the mass spectrometer under the conditions used here. Peaks from minor species corresponding to complexes between the protein and the oligosaccharides are, however, also observed. The possibility that the latter arise from novel covalent enzyme-saccharide complexes is discussed.
本文描述了一种突变型母鸡溶菌酶的产生，其中催化重要残基之一的天冬氨酸-52被丝氨酸取代。该突变酶具有非常低的催化活性，但核磁共振研究表明其结构与野生型蛋白非常相似。核磁共振实验还表明，突变酶活性位点结合有GlcNAc4和GlcNAc6时会形成明确的复合物。已使用电喷雾质谱法（ESMS）对这些复合物进行了检测。最强的峰来自未复合的蛋白质，表明在此处使用的条件下，质谱仪中发生了解离。然而，也观察到了与蛋白质和寡糖之间的复合物相对应的次要物种的峰。本文讨论了后者可能来自新型共价酶 - 糖复合物的可能性。
