Borges T, Glauert H P, Robertson L W
Graduate Center for Toxicology, University of Kentucky, Lexington 40506-0054.
Toxicol Appl Pharmacol. 1993 Jan;118(1):8-15. doi: 10.1006/taap.1993.1003.
The mechanisms of the inhibition of hepatic peroxisomal beta-oxidation by the peroxisome proliferator PFDA3 were studied. Female Sprague Dawley rats were given a single ip injection of either 0, 10, or 40 mg/kg PFDA or were placed on a diet supplemented with the peroxisome proliferator ciprofibrate (0.01%). After 2 weeks, the rats were killed, and hepatic peroxisomes were isolated by discontinuous sucrose gradient centrifugation. Treatment of rats with either PFDA or ciprofibrate increased the individual activities of each of the enzymes in the peroxisomal beta-oxidation pathway. Similarly, treatment of rats with ciprofibrate greatly increased total peroxisomal beta-oxidation, but peroxisomal beta-oxidation was slightly decreased in rats treated with 40 mg/kg PFDA. In vitro inhibition studies found that PFDA was a noncompetitive and reversible inhibitor of both the activities of the peroxisomal bifunctional protein, namely enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase. The Ki of the inhibition was approximately 5 microM. PFDA only slightly inhibited the activity of peroxisomal fatty acyl CoA oxidase, and did not inhibit peroxisomal thiolase activity. We therefore conclude that PFDA inhibits peroxisomal beta-oxidation by noncompetitively inhibiting the peroxisomal bifunctional enzyme.
研究了过氧化物酶体增殖剂PFDA3抑制肝脏过氧化物酶体β-氧化的机制。给雌性Sprague Dawley大鼠单次腹腔注射0、10或40 mg/kg的PFDA，或使其食用添加了过氧化物酶体增殖剂环丙贝特（0.01%）的饲料。2周后，处死大鼠，通过不连续蔗糖梯度离心分离肝脏过氧化物酶体。用PFDA或环丙贝特处理大鼠均增加了过氧化物酶体β-氧化途径中各酶的个体活性。同样，用环丙贝特处理大鼠大大增加了总的过氧化物酶体β-氧化，但用40 mg/kg PFDA处理的大鼠过氧化物酶体β-氧化略有下降。体外抑制研究发现，PFDA是过氧化物酶体双功能蛋白（即烯酰辅酶A水合酶和3-羟酰基辅酶A脱氢酶）活性的非竞争性可逆抑制剂。抑制的Ki约为5 microM。PFDA仅轻微抑制过氧化物酶体脂肪酰辅酶A氧化酶的活性，不抑制过氧化物酶体硫解酶的活性。因此，我们得出结论，PFDA通过非竞争性抑制过氧化物酶体双功能酶来抑制过氧化物酶体β-氧化。
