Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal.
Exp Parasitol. 2011 Dec;129(4):402-8. doi: 10.1016/j.exppara.2011.08.008. Epub 2011 Aug 16.
Leishmania infantum glyoxalase II shows absolute specificity towards its trypanothione thioester substrate. In the previous work, we performed a comparative analysis of glyoxalase II structures determined by X-ray crystallography which revealed that Tyr291 and Cys294, absent in the human homologue, are essential for substrate binding. To validate this trypanothione specificity hypothesis we produced a mutant L. infantum GLO2 enzyme by replacing Tyr291 and Cys294 by arginine and lysine, respectively. This new enzyme is capable to use the glutathione thioester substrate, with kinetic parameters similar to the ones from the human enzyme. Substrate specificity is likely to be mediated by spermidine moiety binding, providing a primer for understanding the molecular basis of trypanothione specificity.
婴儿利什曼原虫甘油醛-3-磷酸脱氢酶 II 对其硫醇酯底物具有绝对特异性。在之前的工作中，我们通过 X 射线晶体学对甘油醛-3-磷酸脱氢酶 II 结构进行了比较分析，结果表明，人同源物中缺失的 Tyr291 和 Cys294 对于底物结合是必不可少的。为了验证这个 trypanothione 特异性假说，我们通过分别用精氨酸和赖氨酸替换 Tyr291 和 Cys294，产生了一种突变的婴儿利什曼原虫 GLO2 酶。这种新的酶能够使用谷胱甘肽硫酯底物，其动力学参数与人类同工酶相似。底物特异性可能由亚精胺部分的结合介导，为理解 trypanothione 特异性的分子基础提供了一个起点。
