Ponces Freire A, Ferreira A, Gomes R, Cordeiro C
Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Edíficio C8 1749-016 Lisbon, Portugal.
Biochem Soc Trans. 2003 Dec;31(Pt 6):1409-12. doi: 10.1042/bst0311409.
Saccharomyces cerevisiae is an outstanding cellular model for metabolic studies in glycation. Due to its high glycolytic activity, it produces methylglyoxal, a highly reactive intracellular glycation agent, at a rate of approx. 0.1% of the glycolytic flux. We investigated methylglyoxal metabolism in Saccharomyces cerevisiae cells, using haploid null mutants. Growth studies showed that the most sensitive strains to 2-oxoaldehydes were the null mutants for GSH1 and GLO1, coding for glutathione synthase I and glyoxalase I respectively. The GRE3 null mutant, lacking aldose reductase activity, is as sensitive as the control strain. Kinetic modelling and computer simulation of this type of experiment were also performed, and we concluded that the most important parameters for controlling the intracellular concentration of methylglyoxal are the activity of glyoxalase I and the GSH concentration. Moreover, our model predicts an intracellular steady-state concentration of methylglyoxal of approx. 2 microM. Our results show that the glyoxalase pathway is the main detoxification pathway for 2-oxoaldehydes in yeast, and is likely to be the key enzymatic anti-glycation agent in these cells.
酿酒酵母是糖基化代谢研究中一个出色的细胞模型。由于其高糖酵解活性，它会以约糖酵解通量0.1%的速率产生甲基乙二醛，一种高反应性的细胞内糖基化剂。我们使用单倍体缺失突变体研究了酿酒酵母细胞中的甲基乙二醛代谢。生长研究表明，对2-氧代醛最敏感的菌株是分别编码谷胱甘肽合酶I和乙二醛酶I的GSH1和GLO1的缺失突变体。缺乏醛糖还原酶活性的GRE3缺失突变体与对照菌株一样敏感。我们还进行了这类实验的动力学建模和计算机模拟，并且得出结论，控制细胞内甲基乙二醛浓度的最重要参数是乙二醛酶I的活性和谷胱甘肽浓度。此外，我们的模型预测细胞内甲基乙二醛的稳态浓度约为2微摩尔。我们的结果表明，乙二醛酶途径是酵母中2-氧代醛的主要解毒途径，并且很可能是这些细胞中的关键酶促抗糖基化剂。
