The effect of contaminant proteases in testicular hyaluronidase preparations on the immunological properties of bovine nasal cartilage proteoglycan

Commercial testicular hyaluronidase preparations are contaminated by a small amount of protease activity which is partially inhibited by serine-protease inhibitors or pepstatin. These protease inhibitors can be shown by Sepharose gel column chromatography to abolish or reduce hyaluronidase-induced degradation of bovine nasal cartilage proteoglycan subunit without affecting the ability of the enzyme to degrade chondroitin sulfate. In addition, immunodiffusion studies indicate that pretreatment of hyaluronidase with these protease inhibitors reduces or abolishes the ability of the enzyme to produce a second "link-related" immunoprecipitin line upon digestion of link protein-containing proteoglycan fractions. Thus, the enhancement of immune reactivity and the unmasking of an additional antigen noted after digestion of cartilage proteoglycan with testicular hyaluronidase are most likely due to the exposure of additional antigenic sites or to the release of more highly immuno-reactive fragments by the contaminant proteases rather than to the action of hyaluronidase itself.