Regulation of T4 phage aerobic ribonucleotide reductase - Simultaneous assay of the four activities

被引:21
作者
Hendricks, SP [1 ]
Mathews, CK [1 ]
机构
[1] OREGON STATE UNIV,DEPT BIOCHEM & BIOPHYS,CORVALLIS,OR 97331
关键词
D O I
10.1074/jbc.272.5.2861
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
We have devised an assay procedure that permits simultaneous monitoring of the four activities of ribonucleotide reductase. Using this assay, we have compared the reduction of all four substrates by the T4 bacteriophage aerobic ribonucleotide reductase within different allosteric environments. Specifically, we compared the relative turnover rates by the enzyme when activated with ''in vivo'' concentrations of the known allosteric effecters versus activation by ATP alone. Consistent with the known allosteric properties of this enzyme, our results show that ATP does act as a general activator, although the rate of purine nucleotide reduction was approximately 5% of the rate for the pyrimidine nucleotides. However, addition of the allosteric effecters at their estimated physiological concentrations dramatically changed the relative rates of substrate reduction, creating a more ''balanced'' pool of products. Addition of the substrates at their respective in vivo concentrations further pushed rates of product formation toward a ratio similar to the base composition of the T4 genome. The similarity of the product profile produced under in vivo conditions to the genomic composition of T4 phage is discussed.
引用
收藏
页码:2861 / 2865
页数:5
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