过氧化氢诱导牛晶状体钠钾ATP酶解偶联
H2O2-induced uncoupling of bovine lens Na+,K+-ATPase.
作者信息
Garner W H, Garner M H, Spector A
出版信息
Proc Natl Acad Sci U S A. 1983 Apr;80(7):2044-8. doi: 10.1073/pnas.80.7.2044.
A 1-hr exposure of bovine lenses in organ culture to H2O2 concentrations in the range found in the aqueous fluid of patients with cataracts inhibits 86Rb+ influx. At 1 mM H2O2, complete inhibition was observed and further investigated. Membrane permeability is slightly decreased. Although lactate concentrations increase 2-fold, lens ATP concentrations decrease approximately equal to 10%, suggesting that glycolysis may be stimulated but ATP production is not able to keep up with the demand for energy. Examination of epithelial cell Mg2+-stimulated Na+,K+-ATPase isolated from the cultured lenses indicates H2O2-induced modification. At 5 mM MgATP, ATP hydrolysis is accelerated 30%; at 3 mM MgATP, hydrolysis is normal; and at 0.75 mM MgATP, it is inhibited 75%. p-Nitrophenyl phosphate hydrolysis and eosin maleimide binding indicate that K+ control of the enzyme is modified. Thus, a very early effect of H2O2 upon the lens, well before the formation of opacity, appears to be the uncoupling of Na+ and K+ transport from ATP hydrolysis.
将牛晶状体置于器官培养液中，暴露于白内障患者房水内存在的过氧化氢浓度范围内1小时，会抑制⁸⁶Rb⁺内流。在1 mM过氧化氢时，观察到完全抑制并进行了进一步研究。膜通透性略有降低。虽然乳酸浓度增加了2倍，但晶状体ATP浓度下降约10%，这表明糖酵解可能受到刺激，但ATP生成无法满足能量需求。对从培养的晶状体中分离出的上皮细胞Mg²⁺刺激的Na⁺,K⁺-ATP酶的检测表明存在过氧化氢诱导的修饰。在5 mM MgATP时，ATP水解加速30%；在3 mM MgATP时，水解正常；在0.75 mM MgATP时，水解被抑制75%。对硝基苯磷酸水解和曙红马来酰亚胺结合表明该酶的钾离子调控发生了改变。因此，在晶状体浑浊形成之前，过氧化氢对晶状体的一个非常早期的作用似乎是使Na⁺和K⁺转运与ATP水解解偶联。
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