Poulos A, Beckman K
Clin Chim Acta. 1979 Jul 2;95(1):113-21. doi: 10.1016/0009-8981(79)90343-7.
Some of the properties of the cerebroside sulphate sulphatase of human leucocyte extracts have been studied. The enzyme has an apparent KM of 2.9 mmol/l and is inhibited by the products of the reaction, sulphate and galactocerebroside. A number of divalent metal ions including manganese and magnesium stimulated the reaction only slightly at 5 mmol/l but inhibited strongly at 20 mmol/l. Triton X-100 present in leucocyte extracts also inhibited, increasing both the apparent KM and Vmax. The enzyme activity was dependent on the presence of anionic detergents. At low substrate concentrations a crude taurocholate preparation was the most active of all bile acids examined. Pure taurocholate and sodium cholate were considerably less active. At highter substrate concentrations however, sodium cholate produced the greatest stimulation of enzyme activity. These data suggest that the bile acid/substrate ratio may be a critical factor in determining cerebroside sulphate sulphatase activity at different substrate concentrations.
已对人白细胞提取物中的脑硫脂硫酸酯酶的一些特性进行了研究。该酶的表观 Km 为 2.9 mmol/L，且受到反应产物硫酸根和半乳糖脑苷脂的抑制。包括锰和镁在内的多种二价金属离子在 5 mmol/L 时对反应仅有轻微刺激，但在 20 mmol/L 时则强烈抑制。白细胞提取物中存在的 Triton X - 100 也有抑制作用，会增加表观 Km 和 Vmax。酶活性依赖于阴离子去污剂的存在。在低底物浓度下，粗制牛磺胆酸盐制剂在所检测的所有胆汁酸中活性最高。纯牛磺胆酸盐和胆酸钠的活性则低得多。然而，在较高底物浓度下，胆酸钠对酶活性的刺激作用最大。这些数据表明，胆汁酸/底物比例可能是决定不同底物浓度下脑硫脂硫酸酯酶活性的关键因素。
