氮源对粗糙脉孢菌中谷氨酰胺和丙氨酸生物合成的影响。一项体内¹⁵N核磁共振研究。

Effect of the nitrogen source on glutamine and alanine biosynthesis in Neurospora crassa. An in vivo 15N nuclear magnetic resonance study.

作者信息

Kanamori K, Legerton T L, Weiss R L, Roberts J D

出版信息

J Biol Chem. 1982 Dec 10;257(23):14168-72.

Abstract

The influences of different nitrogen sources on the relative rates of biosynthesis of glutamine and alanine have been studied by 15N nuclear magnetic resonance spectroscopy of intact Neurospora crassa mycelia suspensions. The rate of glutamine synthesis was fastest after growth in media deficient in free ammonium ion, whereas it was slowest following growth in media containing both glutamic acid and glutamine. The reverse trend was observed for the biosynthesis of alanine. A competition between the two biosynthetic pathways for the same substrate, glutamic acid, was found to limit the rate of alanine synthesis when glutamine synthesis was rapid. The observed in vivo rates of these reactions are compared to the reported specific activities of the enzymes catalyzing the reactions, and implications of these results for nitrogen regulation of these pathways under various physiological conditions are discussed.

摘要

通过对完整的粗糙脉孢菌菌丝体悬浮液进行15N核磁共振光谱分析，研究了不同氮源对谷氨酰胺和丙氨酸生物合成相对速率的影响。在缺乏游离铵离子的培养基中生长后，谷氨酰胺合成速率最快，而在同时含有谷氨酸和谷氨酰胺的培养基中生长后，谷氨酰胺合成速率最慢。丙氨酸生物合成则呈现相反的趋势。当谷氨酰胺合成迅速时，发现这两条生物合成途径对同一底物谷氨酸的竞争限制了丙氨酸的合成速率。将这些反应在体内观察到的速率与报道的催化这些反应的酶的比活性进行了比较，并讨论了这些结果对各种生理条件下这些途径氮调节的意义。