Control of the Hyaluronidase Activity Towards Hyaluronan by Formation of Electrostatic Complexes: Fundamental and Application Relevance - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 140

increase in BT-HAase activity between pH 3.5 and 5 reported by Gacesa et al. (1981)
when they increased the sodium chloride concentration from 0.176 to 0.44 mol l -1 .
Figure 11. pH-dependence of the HA hydrolysis catalyzed by BT-HAase in 5 mmol l -1 sodium
chloride and at 37°C, for different BSA concentrations ranging from 0 to 4 g l -1 . The HA concentration
was 1 g l -1 and the BT-HAase concentration was 0.5 g l -1 . The number average molar mass of HA was
0.97 × 10 6 g mol -1 . Data from Lenormand et al. (2010a).
In fact, to be able to characterize the intrinsic HAase activity, the formation of
electrostatic complexes involving either HA and/or HAase should be avoided. From
the experimental point of view, the only way to achieve this is the use of a high level
of ionic strength. According to our results (Figure 4), ionic strength should be higher
than 0.15 mol l -1 , an ionic strength level usually considered as to be the physiological
one. This probably constitutes one of the key reasons which allowed some authors in
the recent years to detect BT-HAase and human testicular HAase (pH-20) activities
at pH values equal to or higher than 7 (Franzmann et al., 2003; Hofinger et al., 2008).
For example, by using an ionic strength of at least 0.25 mol l -1 and 0.2 g l -1 BSA, Fran-
zmann et al. (2003) found an enzymatic activity for the human testicular HAase only
about 2.5 lower at pH 8 than at pH 4.5.