Hulcher F H, Margolis R D, Bowman D J
Biochim Biophys Acta. 1978 Jun 23;529(3):409-18. doi: 10.1016/0005-2760(78)90085-1.
Cholesterol-7alpha-hydroxylase in African green monkey liver had an apparent Km of 1.65-10(-4) M cholesterol and a pH optimum of 7.4. The amplitudes of the circadian maxima of enzyme activity and serum cortisol levels were significantly greater in vervets than in grivets. Fluctuations in enzyme activity and cortisol levels during the circadian cycle were positively correlated (r = 0.89). Enzyme activities and hormone levels were 2.7-fold lower over a 24-h period in the grivet than in the vervet. Cholesterol feeding reduced the enzyme activity by 40% and serum cortisol was reduced to 38% of control levels at the diurnal peak. Serum glucocorticoids may be important physiological regulators of cholesterol-7alpha-hydroxylase in non-human primates. The concentration of cortisol and its time of release appear to be factors in the hyperresponsive trait of grivets. Genetic differences between vervet and grivet races may account for differences in the amplitude and timing of the circadian rhythm of cholesterol-7alpha-hydroxylase activity possibly influenced by cortisol.
非洲绿猴肝脏中的胆固醇7α-羟化酶对胆固醇的表观Km值为1.65×10⁻⁴ M，最适pH为7.4。黑长尾猴中酶活性和血清皮质醇水平的昼夜最大值幅度显著高于灰绿长尾猴。昼夜周期中酶活性和皮质醇水平的波动呈正相关（r = 0.89）。在24小时内，灰绿长尾猴的酶活性和激素水平比黑长尾猴低2.7倍。喂食胆固醇可使酶活性降低40%，在昼夜高峰时血清皮质醇降至对照水平的38%。血清糖皮质激素可能是非人类灵长类动物中胆固醇7α-羟化酶的重要生理调节因子。皮质醇的浓度及其释放时间似乎是灰绿长尾猴高反应性特征的因素。黑长尾猴和灰绿长尾猴种族之间的遗传差异可能解释了胆固醇7α-羟化酶活性昼夜节律的幅度和时间差异，这可能受皮质醇影响。
