Berglund L, Björkhem I, Angelin B, Einarsson K
Acta Chem Scand B. 1986 Jul;40(6):457-61. doi: 10.3891/acta.chem.scand.40b-0457.
The activity of cholesterol 7 alpha-hydroxylase in rat liver microsomes was investigated under conditions favourable for phosphorylation-dephosphorylation. The enzyme activity was similar in the presence or absence of sodium fluoride during preparation. Preincubation with ATP and magnesium did not affect the enzyme activity. Cholesterol 7 alpha-hydroxylase was inhibited by alkaline phosphatase, but this inhibition was similar also after inactivation of the phosphatase. Under similar conditions, rat hepatic hydroxymethylglutaryl CoA reductase activity was clearly modulated in agreement with phosphorylation-dephosphorylation. The absence of such a modulation of cholesterol 7 alpha-hydroxylase argues against involvement of phosphorylation-dephosphorylation in the regulation of this enzyme.
在有利于磷酸化-去磷酸化的条件下，对大鼠肝微粒体中胆固醇7α-羟化酶的活性进行了研究。在制备过程中，无论有无氟化钠存在，酶活性均相似。与ATP和镁预孵育不影响酶活性。胆固醇7α-羟化酶被碱性磷酸酶抑制，但在磷酸酶失活后这种抑制作用也相似。在相似条件下，大鼠肝脏羟甲基戊二酰辅酶A还原酶的活性根据磷酸化-去磷酸化明显受到调节。胆固醇7α-羟化酶不存在这种调节表明磷酸化-去磷酸化不参与该酶的调节。
