Comparison of the inhibition by phospho(enol)pyruvate and phosphoglycolate of phosphofructokinase from B. stearothermophilus.
Comparison of the inhibition by phospho(enol)pyruvate and phosphoglycolate of phosphofructokinase from B. stearothermophilus.
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DOI：
10.1006/abbi.1994.1032
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发表时间：
1994
影响因子：
3.9
通讯作者：
V. L. Tlapak-Simmons;G. Reinhart
中科院分区：
文献类型：
--
作者：
V. L. Tlapak-Simmons;G. Reinhart
比较了磷酸烯醇丙酮酸（PEP）和磷酸乙醇酸（PG）对嗜热脂肪芽孢杆菌磷酸果糖激酶（PFK）的抑制作用。这两种抑制剂通过降低酶对其底物果糖6-磷酸（Fru-6-P）的表观亲和力而起作用，而对Vmax几乎没有影响。然而，这两种配体不同的酶的亲和力和拮抗随后的结合的Fru-6-P的有效性。虽然PG结合约10倍低的亲和力，它拮抗的结合Fru-6-P 3.5倍更强烈地比PEP。此外，焓和熵的贡献之间的抑制剂和Fru-6-P，从这些拮抗作用的耦合自由能，揭示了更大的配体之间的差异。这些数据表明，因此，PFK的结构变化从B。由PG结合产生嗜热脂肪菌，这已经通过X射线晶体学确定（T. Schirmer和P.R. Evans，1990 Nature 343，140-145），可能无法与PEP结合产生的那些相比较，因此不代表一般的“T-状态”，如已经假定的。
A comparison between the inhibition by phospho(enol)pyruvate (PEP) versus the inhibition by phosphoglycolate (PG) of phosphofructokinase (PFK) from Bacillus stearothermophilus is presented. Both inhibitors act by decreasing the apparent affinity displayed by the enzyme for its substrate fructose 6-phosphate (Fru-6-P) while having little effect on Vmax. However, the two ligands differ in both their affinity for the enzyme and their effectiveness at antagonizing the subsequent binding of Fru-6-P. Although PG binds with approximately 10-fold lower affinity, it antagonizes the binding of Fru-6-P 3.5-fold more strongly than does PEP. Moreover, the enthalpy and entropy contributions to the coupling free energy between inhibitor and Fru-6-P, from which these antagonisms derive, reveal even greater differences between the ligands. These data indicate, therefore, that the changes in the structure of PFK from B. stearothermophilus that result from PG binding, which have been determined by X-ray crystallography (T. Schirmer and P. R. Evans, 1990 Nature 343, 140-145), may not be comparable to those that result from PEP binding and consequently do not represent the generic "T-state," as has been presumed.