Hassan A S, Ventling B L
University of Illinois, Department of Veterinary Biosciences, Urbana 61801.
Res Commun Chem Pathol Pharmacol. 1987 Oct;58(1):41-51.
The effect of diabetes on the activity of hepatic cholesterol 7 alpha-hydroxylase (CH-7 alpha) was studied in reconstituted systems using partially purified cytochrome P-450 (P-450) from control and diabetic rat livers. With both preparations, the rate of product formation increased when the amount of P-450 in the incubations was increased. However, the increase in the rate of product formation was greater with the control P-450. When varying levels of dithiothreitol (DTT) were added to the incubations, the specific activity of the control P-450 was found to be directly proportional to the concentration of DTT. However, DTT did not have any consistent effect on the specific activity of the diabetic P-450. Finally, while 25 mM NaF in the incubation medium had minimal effect on the specific activity of the control P-450, the specific activity of the diabetic P-450 increased by 32% in the presence of 25 mM NaF. These studies have shown some important differences in the properties of CH-7 alpha in control and diabetic animals and emphasize the need to study the enzyme under more defined conditions.
利用从对照大鼠和糖尿病大鼠肝脏中部分纯化的细胞色素P-450（P-450），在重组系统中研究了糖尿病对肝脏胆固醇7α-羟化酶（CH-7α）活性的影响。对于这两种制剂，当孵育中P-450的量增加时，产物形成速率增加。然而，对照P-450使产物形成速率的增加更大。当向孵育体系中加入不同水平的二硫苏糖醇（DTT）时，发现对照P-450的比活性与DTT浓度成正比。然而，DTT对糖尿病P-450的比活性没有任何一致的影响。最后，虽然孵育培养基中25 mM NaF对对照P-450的比活性影响最小，但在25 mM NaF存在下，糖尿病P-450的比活性增加了32%。这些研究表明，对照动物和糖尿病动物中CH-7α的性质存在一些重要差异，并强调需要在更明确的条件下研究该酶。
