Glucocerebrosidase: stoichiometry of association between effector and catalytic proteins

Abstract

1. The effector and catalytic proteins of glucocerebrosidase associated in the presence of acidic phospholipid to give active enzyme. 2. At optimum concentrations of acidic phospholipid (about 0.15 mM), the association reached equilibrium instantaneously. 3. From the experimental data, a tentative model of the association was deduced. This involved a two-step complex formation. When the effector concentration was limiting, a simple binary complex was formed between one molecule each of effector and catalytic proteins; the reaction proceeded rapidly to completion. When the effector was in excess, a ternary complex was formed by the addition of another molecule of effector; this reaction did not go to completion and was characterised by a finite equilibrium constant. 4. The experimental data were curve fitted to an equation derived from the model