The invention provides truncated biologically active ADAMTS polypeptides, particularly those with hyalectenase activity, and more particularly those with aggrecanase activity, that exhibit greater stability and homogeneity and higher expression yields than their full-length counterparts. The invention also provides nucleic acid molecules encoding such truncated biologically active ADAMTS polypeptides and methods for producing the truncated biologically active ADAMTS polypeptides. In addition, the invention provides methods for identifying compounds capable of modulating biologically active ADAMTS polypeptides, particularly those compounds that inhibit aggrecanase activity.