Human β-glucosidase: inhibition by sulphates and purification by affinity chromatography on dextran-sulphate-sepharose

The acid β-glucosidase (d-glucosyl-N-acylsphingosine glucohydrolase, EC 3.2.1.45) from human placenta is inhibited by sulphated macromolecules such as Dextran sulphate or chondroitin sulphate. This inhibition is alleviated by compounds such as crude traurocholate or phospholipids, which are known activators of acid β-glucosidase. Partially-purified human β-glucosidase will bind to Dextran sulphate linked to Sepharose 4B and can be eluted with low concentrations of crude sodium taurocholate. This procedure gives a 10-15 fold purification with good yield and has been included in a scheme giving an approx. 4000-fold purification of placental β-glucosidase. Evidence is presented which suggests that phospholipids bind to β-glucosidase by both ionic and hydrophobic interactions. The inhibition of enzyme activity caused by sulphated compounds and non-ionic detergents may be attributed to interference with, respectively, the ionic and hydrophobic binding of phospholipid to the enzyme.