Gutierrez-Correa J, Stoppani A O
Bioenergetics Research Centre, School of Medicine, University of Buenos Aires, Argentina.
Free Radic Res. 1995 Mar;22(3):239-50. doi: 10.3109/10715769509147543.
Copper Fenton systems (Cu(II)/H2O2 and Cu(II)/Asc) inactivated the lipoamide reductase and enhanced the diaphorase activity of pig-heart lipoamide dehydrogenase (LADH). Cupric ions alone were less effective. As a result of Cu(II)/H2O2 treatment, the number of titrated thiols in LADH decreased from 6 to 1 per subunit. NADH and ADP (not NAD+ or ATP) enhanced LADH inactivation by Cu(II). NADH also enhanced the effect of Cu(II)/H2O2. Dihydrolipoamide, dihydrolipoic acid, Captopril, acetylcysteine, EDTA, DETAPAC, histidine, bathocuproine, GSSG and trypanothione prevented LADH inactivation. 100 microM GSH, DL-dithiothreitol, N-(2-mercaptopropionylglicine) and penicillamine protected LADH against Cu(II)/Asc and Cu(II), whereas 1.0 mm GSH and DL-dithiothreitol also protected LADH against Cu(II)/H2O2. Allopurinol provided partial protection against Cu(II)/H2O2. Ethanol, mannitol, Na benzoate and superoxide dismutase failed to prevent LADH inactivation by Cu(II)/H2O2 or Cu(II). Catalase (native or denaturated) and bovine serum albumin protected LADH but that protection should be due to Cu binding. LADH inhibited deoxyribose oxidation and benzoate hydroxylation by Cu(II)/H2O2. It is concluded that site-specifically generated HO, radicals were responsible for LADH inactivation by Cu(II) Fenton systems. The latter effect is discussed in the context of ischemia-reoxygenation myocardial injury.
铜芬顿体系（Cu(II)/H₂O₂ 和 Cu(II)/Asc）可使猪心脂酰胺脱氢酶（LADH）的脂酰胺还原酶失活，并增强其黄递酶活性。单独的铜离子效果较差。经 Cu(II)/H₂O₂ 处理后，LADH 每个亚基中可滴定硫醇的数量从 6 个减少至 1 个。NADH 和 ADP（而非 NAD⁺ 或 ATP）可增强 Cu(II) 对 LADH 的失活作用。NADH 还增强了 Cu(II)/H₂O₂ 的作用效果。二氢硫辛酰胺、二氢硫辛酸、卡托普利、乙酰半胱氨酸、EDTA、DETAPAC、组氨酸、邻二氮菲、GSSG 和锥虫噻吨可防止 LADH 失活。100 μM 的 GSH、DL-二硫苏糖醇、N-(2-巯基丙酰基)甘氨酸和青霉胺可保护 LADH 免受 Cu(II)/Asc 和 Cu(II) 的影响，而 1.0 mM 的 GSH 和 DL-二硫苏糖醇也可保护 LADH 免受 Cu(II)/H₂O₂ 的影响。别嘌呤醇可部分保护 LADH 免受 Cu(II)/H₂O₂ 的影响。乙醇、甘露醇、苯甲酸钠和超氧化物歧化酶无法防止 Cu(II)/H₂O₂ 或 Cu(II) 对 LADH 的失活作用。过氧化氢酶（天然或变性）和牛血清白蛋白可保护 LADH，但这种保护作用应归因于铜的结合。LADH 可抑制 Cu(II)/H₂O₂ 引发的脱氧核糖氧化和苯甲酸羟化反应。研究得出结论，位点特异性产生的 HO· 自由基是 Cu(II) 芬顿体系使 LADH 失活的原因。在缺血-再灌注心肌损伤的背景下讨论了后者效应。
