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 125

conditions, this linear polymer has high molar mass, usually exceeding 10 6 g mol -1
(2,500 disaccharide units) with values reaching 10 × 10 6 g mol -1 (25,000 disaccharide
units) as, for example, in synovial fluid (Noble, 2002). However, HA molar mass var-
ies according to the species and the tissue and, even in a given tissue, it can have a
great polydipersity (Laurent, 1987).
Figure 1. Chemical structure of HA: D-glucuronic acid- b (1,3)-N-acetyl-D-glucosamine disaccharide
units linked through b (1,4) glycosidic bonds (Deschrevel, in press).
While HA has long been considered as an inert component acting only as a space
filler, it is now established that HA has many biological functions related to its unique
biophysicochemical properties, among which, its viscoelastic behavior (Cowman and
Matsuoka, 2005; Fouissac et al., 1993) and its ability to retain large amount of water
(Laurent, 1970) and to interact with various molecular species (Hardingham and Muir,
1972; Hascall and Heinegard, 1974; Pasquali-Ronchetti et al., 1997; Underhill and
Toole, 1979). The HA is actually an excellent space-filling molecule able to adjust
to surfaces and to act as a lubricant. It can undergo deformation, as required dur-
ing growth and tissue remodelling, and has energy-absorbing properties, as required
for energy dissipation under dynamic shock imposed to articulations (Cowman and
Matsuoka, 2005; Lapčik Jr. et al., 1998; Laurent and Fraser, 1992). The HA plays a
significant role in the water homeostasis of the tissues and contributes to the regu-
lation of the distribution and transport of smalls ions and proteins (Gribbon et al.,
1999; Laurent, 1987; Laurent and Ogston, 1963). The HA provides a scafold on which
various molecular species can reversibly assemble. In particular, HA forms aggregates
with proteoglycans containing sulfated polysaccharides, such as chondroitin sulfate
and keratan sulfate (Hardingham and Muir, 1972; Hascall and Heinegard, 1974). The