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 135

Figure 7. Generalized BSA-dependence of the HA hydrolysis catalyzed by BT-HAase. The dashed
lines allow to distinguish between the four characteristic domains of the curve, and A, B and C are
characteristic BSA concentrations corresponding to the junctions between the domains (see text).
Model curve from Lenormand et al. (2009).
The effects of serum proteins, in particular BSA, on HAase activity were already
reported by some authors. According to the first studies, reviewed by Mathews and
Dorfman (1955), serum, whatever its origin, inhibited HAase. Such inhibitions may
be explained by the fact that the total protein concentration in serum was high as com-
pared to the HA and HAase concentrations used, so that the formation of electrostatic
complexes between HA and many serum proteins reduced the concentration of HA
b(1,4) bonds accessible to HAase. On the contrary, Gacesa et al. (1981) observed a
marked enhancement of BT-HAase activity upon addition of serum to incubation mix-
tures at pH below 5 and in the presence of 0.1 mol l -1 sodium chloride. These authors
noted that the extent of activation was largely dependent upon the ratio of enzyme over
serum quantities. They further showed that the greatest activation effect was obtained
by using BSA or human serum albumin. Gold (1982) showed that both BT-HAase and
human liver HAase exhibited increased activity in the presence of BSA at pH 4. All
these observations are in total agreement with our above-mentioned results.