人前列腺酸性磷酸酶催化的磷酸（氧）-水交换反应。
Phosphate (oxygen)-water exchange reaction catalyzed by human prostatic acid phosphatase.
作者信息
Van Etten R L, Risley J M
出版信息
Proc Natl Acad Sci U S A. 1978 Oct;75(10):4784-7. doi: 10.1073/pnas.75.10.4784.
Conclusive evidence is presented that an acid phosphatase catalyzes phosphate (oxygen)-water exchange. Studies conducted with human prostatic acid phosphatase by two independent methods have established that, despite earlier reports to the contrary, the enzyme catalyzes an exchange reaction between oxygen atoms of phosphate ion and of water. Kinetic data were obtained both by chemical conversion to trimethyl phosphate followed by mass spectroscopy and by a totally independent method involving 31P isotope shift nuclear magnetic resonance spectroscopy. Analysis showed that the enzyme catalyzes the exchange in a random, noncoupled process. If any coupled exchange occurs, it must represent less than 10% of the total. By mass spectral analysis, catalytic rate constants kcat = 0.14 sec-1 (4 degrees) and 1.8 sec-1 (37.5 degrees) were obtained. By 31P nuclear magnetic resonance kcat = 1.6 sec-1 (31 degrees) was obtained. The energy of activation for the exchange reaction is approximately 13kcal mol-1. The kcat value for exchange is about 10-fold greater than that observed with Escherichia coli alkaline phosphatase.
有确凿证据表明，一种酸性磷酸酶催化磷酸（氧）-水交换反应。通过两种独立方法对人前列腺酸性磷酸酶进行的研究证实，尽管早期有相反报道，但该酶催化磷酸根离子的氧原子与水之间的交换反应。动力学数据通过化学转化为磷酸三甲酯后进行质谱分析以及通过一种完全独立的涉及³¹P同位素位移核磁共振光谱的方法获得。分析表明，该酶以随机、非偶联过程催化交换反应。如果存在任何偶联交换，其占总量的比例必定小于10%。通过质谱分析，获得催化速率常数kcat = 0.14秒⁻¹（4℃）和1.8秒⁻¹（37.5℃）。通过³¹P核磁共振获得kcat = 1.6秒⁻¹（31℃）。交换反应的活化能约为13千卡/摩尔。交换反应的kcat值比大肠杆菌碱性磷酸酶观察到的值大约高10倍。
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