CONTROL OF ESCHERICHIA COLI CARBAMYL PHOSPHATE SYNTHETASE BY PURINE AND PYRIMIDINE NUCLEOTIDES
CONTROL OF ESCHERICHIA COLI CARBAMYL PHOSPHATE SYNTHETASE BY PURINE AND PYRIMIDINE NUCLEOTIDES
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DOI：
10.1021/bi00874a013
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发表时间：
1966-01-01
期刊：
影响因子：
2.9
通讯作者：
MEISTER, A
中科院分区：
文献类型：
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作者：
ANDERSON, PM;MEISTER, A
氨基甲酰磷酸合成酶活性受到许多嘌呤和嘧啶核苷酸的显著影响。嘌呤核苷酸(例如，肌苷一磷酸)刺激活性，而嘧啶核苷酸抑制(尿苷核苷酸)或没有作用(胞苷核苷酸)；这些作用由每条途径中合成的第一个核苷酸发挥最大，并随着分别从肌苷5[图像]一磷酸或尿苷5[图像]一磷酸合成各种核苷酸所需的步骤的增加而减少。核苷酸显然是通过改变酶对三磷酸腺苷(ATP)的亲和力来影响活性的。这些发现与这些发现对嘧啶和精氨酸生物合成以及嘌呤核苷酸生物合成的调节的关系被考虑。我们还考察了不同核苷酸对氨基甲酰磷酸合成酶(依赖碳酸氢根的三磷酸腺苷、[γ]-谷氨酰羟基甲酸酯的水解、由氨基甲酰磷酸和腺苷二磷酸合成三磷酸腺苷)催化的几个附加反应的影响；只有最后两个反应受到显著影响，这表明氨基甲酰磷酸合成的第一步(二氧化碳的活化)并不直接参与这类控制。
Carbamyl phosphate synthetase activity is significantly affected by a number of purine and pyrimidine nucleotides. Purine nucleotides (e.g., inosine monophosphate) stimulated activity and pyrimidine nucleotides were inhibitory (uridine nucleotides) or had no effect (cytidine nucleotides); these effects are exerted maximally by the first nucleotides synthesized in each pathway and decrease as the number of steps required to synthesize the various nucleotides from inosine 5[image]-monophosphate or uridine 5[image]-monophosphate, respectively, increases. The nucleotides apparently affect activity by altering the affinity of the enzyme for adenosine triphosphate (ATP). The relationship of these findings to these findings to the regulation of pyrimidine and arginine biosynthesis and of purine nucleotide biosynthesis is considered. The effects of the various nucleotides on the several additional reactions catalyzed by carbamyl phosphate synthetase (bicarbonate-dependent adenosine triphosphatase, hydrolysis of [gamma]-glutamyl hydroxamate, synthesis of ATP from carbamyl phosphate and adenosine diphosphate) were also examined; only the last 2 of these reactions were significantly affected, suggesting that the first step in carbamyl phosphate synthesis (activation of carbon dioxide) is not directly involved in this type of control.