Effect of heat and pH on hyaluronidase.

Crude preparations of bovine testicular hyaluronidase (1) depolymerize both hyaluronic acid (HA) and chondroitinsulfuric acid (CSA). Since a series of enzyme preparations with a wide range (loo-fold) of purity shows a constant ratio of activities toward both substrates when examined by a turbidimetric method of assay, the conclusion was drawn that both activities were most likely assignable to a single enzyme (2). A like conclusion was drawn from similar comparisons made by Meyer and Rapport (3), who used an assay procedure based upon the measurement of reducing sugars liberated from each substrate. Recently, however, Lillie, Emmart, and Laskey (4) observed that a boiled enzyme solution retained its capacity to depolymerize CSA as indicated by histochemical methods, but not HA as indicated by a turbidimetric procedure. These workers concluded that bovine testicular preparations contain a thermolabile enzyme, hyaluronidase, which depolymerizes hyaluronic acid, in vitro, and a chondromucinase which, while thermolabile at pH 5.5 and 6.5, resists boiling at pH 3. In contrast, Meyer and Rapport (5) noted that testicular hyaluronidase retained 5 per cent of its activity after boiling for 10 minutes. No pH was stated. This report is concerned with a further attempt to elucidate the nature of the two activities of bovine testicular preparations which depolymerize, respectively, HA and CSA.