Kinetic mechanism and divalent metal activation of human erythrocyte pyridoxal phosphatase
作者:Margaret L. Fonda、Yan-na Zhang
DOI:10.1016/0003-9861(95)90018-7
日期:1995.7
Human erythrocyte pyridoxal phosphatase has an essential requirement for divalent cations. Its activation by Mg2+, Co2+, Ni2+, or Mn2+ followed Michaelis-Menten kinetics. Other divalent cations inhibited the enzyme. The kinetic properties of the enzyme were investigated with pyridoxal phosphate and Mg2+ alone and in the presence of the product, Pi, or dead-end inhibitors at pH 7.4 and 37 degrees C
人红细胞吡ido醛磷酸酶对二价阳离子具有基本要求。Mg2 +,Co2 +,Ni2 +或Mn2 +对其的活化遵循Michaelis-Menten动力学。其他二价阳离子抑制了该酶。单独使用吡ido醛磷酸盐和Mg2 +并在产物,Pi或无端抑制剂在pH 7.4和37℃下存在下,用磷酸吡with醛和Mg2 +研究了该酶的动力学特性。在释放产物之前,酶与底物和Mg2 +结合。Pi对底物产生竞争性抑制,而对Mg2 +则产生非竞争性抑制。钼酸盐还是底物的竞争性抑制剂,而Mg2 +是非竞争性抑制剂。Ca2 +对Mg2 +具有竞争性抑制作用,对底物具有非竞争性抑制作用。研究了Mg2 +和底物对多种基团特异性试剂灭活吡x醛磷酸酶的影响。MgCl2增强了碘乙酸盐对酶的灭活作用。在失活分析中确定的酶-Mg复合物的Kd与游离酶对Mg2 +的Km相似,表明Mg2 +与游离酶结合。在不存在或存在Mg2 +的情况下,低浓度