Sources of Hyaluronan

At the present time, it is known that HA is not an inactive macromolecule of connective tissue, but a metabolically highly active biopolymer. Its half-life in the joints is 1-30 weeks, up to 1-2 days in the epidermis and derma and only 2-5 minutes in the bloodstream. In other words, during one day, approximately 5 g of dry HA can be synthesized and cleaved in the body of an adult 70-kg man, one-third of the whole amount of HA in the body [17]. 

The HA polysaccharide chain undergoes degradation by endoglucanase (hyaluronidase) and exoglucanase (beta-glucouronidase and beta-N-acetyl hexosaminidase). The testicle hyaluronidases decompose polysaccharides with a hydrolysis of the glycoside bond to tetra-, octa- and other saccharides. 

It was pointed out that HA was first discovered as an animal polysaccharide, but soon thereafter it was found that the biopolymer also exists among bacteria. In 1937, Kendall, Heidelberger and Dawson reported about extraction of a polysaccharide from the cultural liquid of the haemolytic streptococcus that was precipitated with acetic acid and ethanol [3]. The authors proposed that the isolated biopolymer is identical to hyaluronic acid, a hypothesis that was later confirmed. It was eventually found that the mammalian glycosaminoglycan exists among several groups of the streptococcus, many of which are pathogenic for humans and animals. 

HA was initially produced by extraction from the animal material. Because of the growing demand of HA, however, scientists started looking for new methods for its production, methods that were preferably microbiological. A study of the bacterial synthesis of hyalu-ronan on the free cells level started when UDP-glucose, UDP-N-acetyl glucosamine and UDPP-glucuronic acid were obtained from streptococcus extracts. 

In 1953 Roseman and coworkers published an article in which they describe the precipitation of HA from the cultural liquid (CL) of Group A streptococcus [18]. They reported the yield 200-300 mg from 41 of CL. Later, Warren and Gray found the semi-synthetic media for the cultivation of the HA producers [19]. 

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In this chapter we describe some methods used to determine the kinetics of the action of hyaluronidase. Table 2 presents a survey of the Michaelis-Menten constants (Km) of the action of hyaluronidase on hyaluronan and chondroitin sulfate obtained using different methods. These assays usually make use of hyaluronan as a substrate for hyaluronidase. Various sources of hyaluronan are employed, but these substrates have different physicochemical properties (molecular weight, intrinsic viscosity). Payan et al. [130] investigated the action of Streptomyces hyaluronidase on hyaluronan from several sources. 

Trade name, manufacturer Cross-linked by Source of hyaluronan Hyaluronan cone (mg/ml) Average particle size (gm)... 

The difference between avian-derived (chicken comb tissue) and fermentation-derived sources of hyaluronan is illustrated by comparison of Hylaform and Captique, which differ only in their hyaluronan source. There are no differences between the two products in concentration or particle size, and no difference is claimed or reported in any physical property of the two. 

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