The "a disintegrin and metalloproteinase with thrombospondin motifs" (ADAMTS) enzymes are secreted proteinases involved in development, blood clotting and the turnover of extracellular matrix. Manufacturing recombinant enzyme presents quite a challenge due to the presence of disulphide bridges, the large size and modular structure. A sub-group of these enzymes are known as "aggrecanases" and it is likely that they are involved in a number of pathologies related to increased turnover of the extracellular matrix, particularly in tissues where the concentration of proteoglycans is high, such as cartilage and the central nervous system. We have expressed three of these enzymes, ADAMTS-1, -4 and -5, in insect cells using plasmid-based systems.