Buko V U, Artsukevich A A, Ignatenko K V
Institute of Biochemistry, National Academy of Sciences, Grodno, Belarus.
Exp Toxicol Pathol. 1999 Jul;51(4-5):294-8. doi: 10.1016/S0940-2993(99)80009-8.
The effects of aldehydic products of lipid peroxidation, malondialdehyde (MDA) and 4-hydroxynonenal (HNE), on the structure of rat liver microsomal membrane and cytochrome P-450 was studied. MDA (15-30 microM) similarly to p-chlormercuribenzoate decreased the cytochrome P-450 content by 50 % and lowered microviscosity of lipid surrounding of the spin label OTMB bound to SH-groups of membrane proteins. OTMB was effectively reduced by K3Fe(CN)6 in microsomes preincubated with MDA (20 (M), but not in native microsomes. HNE (10 microM) decreased the cytochrome P-450 content by 90 %. Reduced glutathione and cysteine (5 mM) prevented the decrease of cytochrome P-450 under influence of both MDA or HNE, whereas cytochrome P-420 formation remains unchanged. MDA and HNE decreased activities of NADPH oxidase and NADPH cytochrome c reductase. HNE increased microviscosity of the OTMB lipid environment. The further increase of HNE concentration did not affect this parameter. Both MDA and HNE increased the absorbance at 420 nm, which indicated inactivation of cytochrome P-450 by changes in hydrophobicity of lipid surrounding. We suggest that HNE and aliphatic aldehydes at low concentrations can enter into hydrophobic environment of cytochrome P-450 binding to its SH-groups, which led to inactivation of cytochrome P-450. At the same time, the modification of membrane surface layer and subsequent decrease of hydrophobicity of cytochrome P-450 environment preceded the binding of MDA to SH-groups of cytochrome P-450 to develop its inactivating effect.
研究了脂质过氧化醛类产物丙二醛（MDA）和4-羟基壬烯醛（HNE）对大鼠肝微粒体膜结构和细胞色素P-450的影响。与对氯汞苯甲酸类似，MDA（15 - 30微摩尔）使细胞色素P-450含量降低50%，并降低了与膜蛋白SH基团结合的自旋标记OTMB周围脂质的微粘度。在与MDA（20微摩尔）预孵育的微粒体中，K3Fe(CN)6能有效还原OTMB，但在天然微粒体中则不能。HNE（10微摩尔）使细胞色素P-450含量降低90%。还原型谷胱甘肽和半胱氨酸（5毫摩尔）可防止MDA或HNE作用下细胞色素P-450的减少，而细胞色素P-420的形成保持不变。MDA和HNE降低了NADPH氧化酶和NADPH细胞色素c还原酶的活性。HNE增加了OTMB脂质环境的微粘度。HNE浓度进一步增加对该参数无影响。MDA和HNE均增加了420纳米处的吸光度，这表明细胞色素P-450因周围脂质疏水性变化而失活。我们认为，低浓度的HNE和脂肪醛可进入细胞色素P-450的疏水环境并与其SH基团结合，从而导致细胞色素P-450失活。同时，膜表层的修饰以及随后细胞色素P-450环境疏水性的降低先于MDA与细胞色素P-450的SH基团结合以发挥其失活作用。
