Functional characteristics of the streptococcal deoxyribonuclease ‘streptodornase’, a protein with DNase activity present in the medicament Varidase®

Streptodornase, a streptococcal deoxyribonuclease present as an active constituent of the medicament Varidase®, has been shown to exhibit no activity against RNA and digests native DNA more rapidly than single-stranded DNA. The pH range of streptodornase activity has also been established and the enzyme has been shown to exhibit DNase activity over a wide pH range (5.0–9.0) exhibiting maximal activity at pH 7.8. The effects of temperature on streptodornase activity have also been investigated under a variety of conditions showing the enzyme to be active over a range of 10–60 °C. The data from these temperature studies would suggest the possible existence of semi-denatured ‘meta-stable’ conformations for the streptodornase molecule with reduced levels of DNase activity. The effect of variable substrate concentrations has also been studied to enable the determination of the kinetic constants for this enzyme. The lack of RNAse activity by streptodornase would support data showing a low immunogenic response to Varidase® treatment.