Large scale purification of an almond oleosin using an organic solvent procedure

Oleosins are small proteins which are specific to oil-bodies, the plant org anelles specialized in oil storage. These proteins are thought to stabilize the structure and to prevent the oil droplets from coalescing. Since oleos ins are insoluble in water, they are usually purified either as aggregates in water or as polypeptides solubilized with SDS. These conditions raise ma jor problems for performing biophysical studies, however. We have taken adv antage of the solubility of almond oleosin in chloroform to purify it by di fferential extraction using solvent mixtures. Detergent-free oleosin was pu rified to apparent homogeneity with a purification yield of 20 % using almo nd meal as starting material. An oil-body suspension was reconstituted by s onicating the solvent-purified oleosin with phospholipids and triacylglycer ols. Protease protection experiments suggest that oleosins are inserted int o the reconstituted oil-body as they are in native organelles. This simple purification procedure allows to obtain a detergent-free solution of oleosi n easy to handle which can be used for oil-body reconstitution and biophysi cal studies by the Wilhemly plate method. (C) 2001 Editions scientifiques e t medicales Elsevier SAS.