Human serum hyaluronidase: characterization of a clinical assay

Hyaluronidase, a lysosomal endoglycosidase mediating hyaluronan (hyaluronic acid) turn-over, is thought to be important in many normal developmental and certain pathologic processes. Previous assays of serum hyaluronidase are limited with respect to their applicability for routine clinical chemistry or clinical biochemical genetics applications. We describe a new assay of human serum or plasma hyaluronidase activity based on the determination of released N-acetylglucosamine reducing termini that allows the analysis of the enzyme with small, easily obtained sample volumes. Using 10 microliters of serum or plasma, sodium formate buffer and human umbilical cord hyaluronan as substrate, we found a pH optimum of 3.9 and a K(m) and Vmax of 114 mg/l and 5102 mU/l, respectively. In addition, the assay has excellent linearity, precision and reproducibility.