Patent ID: 7176011

Claim:
A method of determining if a compound is a substrate of an isolated membranous lipid cleavage enzyme complex (LCE), which LCE cleaves a conjugate of the type L-B-D in which: L represents a lipid-like residue, B represents a phosphate bridge or a thiophosphate bridge and D denotes a pharmacologically active substance; or B-D represents a pharmacologically active substance phosphonate and the LCE induces a cleavage of a covalent bond between the lipid moiety L and the residue -B-D; and wherein said LCE has a molecular weight of about 120,000 to about 160,000, as determined by the SDS-PAGE method, is free of phospholipase C activity, is activated by D609 (Tricyclodecan-9-yl-xanthogenat) and is inhibited by Ca 2+ , Zn 2+ or Mn 2+ , said method comprising: a) obtaining the LCE by: i) preparing a homogenate of cells selected from the group consisting of leukocytes, monocytes, tumour cells, kidney cells, lymphocytes, cells of the immuno/lymphatic system, and/or macrophages; ii) isolating plasma membranes from the cell homogenate; and iii) identifying LCE cleavage activity in a fraction of the isolated plasma membranes, whereby LCE cleavage activity indicates presence of LCE in the fraction; b) incubating the LCE with the compound; and c) detecting cleavage products, wherein the presence of cleavage products indicates that the compound is a substrate or a ligand of the LCE.