Truncated aggrecanase proteins and nucleotides sequences encoding them as well as processes for producing them are disclosed. Additionally, aggrecanases with amino acid mutations that lead to increased stability and expression levels in comparison with wild-type or native aggrecanases are also disclosed. Aggrecanases of the invention are especially useful for development of compositions for treatment of diseases such as osteoarthritis. Methods for developing inhibitors of the aggrecanase enzymes and antibodies to the enzymes for treatment of conditions characterized by the degradation of aggrecan are also disclosed.