酵母合成的^(15)NL-色氨酸中N元素代谢通量的分析

Metabolic flux analysis of elemental nitrogen for L-tryptophan biosynthesis in yeast

以葡萄糖为碳源,硫酸铵为氮源,15N邻氨基苯甲酸为前体物,利用酵母发酵合成15N L-色氨酸,是合成15NL-色氨酸的一种新方法。为了有效的利用含氮的化合物,实验过程中,采用15N标记的邻氨基苯甲酸为示踪剂,分析了N元素在15N L-色氨酸合成过程中的代谢通量。结果表明,93%外加的邻氨基苯甲酸被转化为15N L-色氨酸。硫酸铵在促进菌体生长的同时,0.05%硫酸铵被用于合成邻氨基苯甲酸,并进一步被转化为L-色氨酸,5.95%硫酸铵被直接用于合成15N L-色氨酸。

A new synthesis method for ^15N L-tryptophan by yeast fermentation using glucose as carbon source, ammonium sulphate as nitrogen source, and ^15N anthranilic acid as a precursor is described. In order to ensure efficient use of the nitrogen source compounds, the metabolic flux of elemental nitrogen was analyzed for L-tryptophan biosynthesis using the ^15N anthranilic acid as a tracer in the experimental process. The results indicated that 93 % of the L-tryptophan was derived from exogenous anthranilic acid. Ammonium sulphate contributed to the growth of the yeast and anthranilic acid was also synthesized from ammonium sulphate and subsequently converted into L-tryptophan （0.05 % of the total yield）. A further 5.95 % of L-tryptophan was directly synthesized from ammonium sulphate.