Purification and properties of the membrane form of variant surface glycoproteins (VSGs) from Trypanosoma brucei.

Variant surface glycoproteins (VSG) of Trypanosoma brucei are released in a water soluble form on impairment of membrane integrity. We have previously shown that this release is the result of an enzyme-mediated event which converts the hydrophobic membrane form VSG into the hydrophilic water-soluble form. We now present further details of the methods by which membrane form VSG ( mfVSG ) may be isolated, uncontaminated by water-soluble VSG ( sVSG ). The sensitivity to different metal ions of the enzyme that mediated the conversion event is discussed, and some biochemical characteristics of different mfVSG preparations are presented.