HYALURONIDASE OF RAT SKIN

A hyaluronidase demonstrated in rat skin has been purified 75-fold from extracts. The enzyme is an endo-β-acetylhexosaminidase, acts on chondroitin 4- and 6-sulfate at a lesser rate than on hyaluronate, and catalyzes transglycosylation as well as hydrolysis. Optimal activity with hyaluronate occurs at pH 3.7. Smaller hyaluronate oligosaccharides are poor substrates. Enzyme fractions showing some small catalytic differences are separable from skin extracts by ion-exchange chromatography. This finding is extended by electrofocusing experiments, which partially resolve a number of isozymes. These differ by as much as 1.5 pH units in isoelectric point. Viral neuraminidase apparently effects a partial conversion of the more acidic to the less acidic isozymes. Colorimetric assays for hyaluronidase have been modified to overcome interference by β-glucuronidase and β-acetylglucosaminidase, both present in crude tissue extracts. The amount of hyaluronidase that occurs in skin is amply sufficient in itself to account for the rate of catabolism reported for hyaluronate in this tissue. © 1969.