Hyaluronic acid chemical structure

The final Klebsiella polysaccharide that will be mentioned specifically is KZS, whose chemical structure was determined by Niemann et al (24) (Figure 30). This polysaccharide is of particular interesT because its backbone consists of a similar alternating 1, 3 diequatorial, 1, 4 diequatorial glycosidic linkage geometry to that found in the connective tissue polysaccharides, hyaluronic acid, chondroitin sulphate and dermatan sulphate (25). All these three polysaccharides have exhibited 3-fold helical conformations with axially projected chemical repeats in the range 0.95 - 0.97 nm which is comparable to 0.97 nm found in K25 which also forms a 3-fold helix (14). Further, left-handed helices were found to be more favourable in K25 as has previously been observed in the connective tissue polysaccharides. The similarities between these various different structures is apparent in Figure 31 which shows projections down the axis of K25 and several of the connective tissue polysaccharides. 

Compounds known to behave in this way in vivo are listed in recent reviews in this Series.1 2 The structures of some of the /3-D-glucopyranosiduronic acids isolated from urine have been proved by chemical synthesis.3 A few similar derivatives of flavones and triterpenes have been isolated from plants. D-Glucuronic acid also occurs in mammalian tissues as a constituent of acid mucopolysaccharides (aminodeoxypolysaccharides, containing uronic acid), such as hyaluronic acid, chondroitinsulfate, and heparin,4 and it is a direct precursor of L-ascorbic acid in plants and mammals.6 It is present in many of the plant polysaccharides classified as hemicelluloses6 and gums,7 and it has also been found in certain bacterial polysaccharides.4... 

Hyaluronan was identified by Karl Meyer11 in 1938 as a hexuronic acid-containing material that also provided the turgor for the vitreous of the eye. The name hyaluronic acid was proposed from the Greek hyalos (glassy, vitreous) and uronic acid. It required 20 years however before the chemical structure of HA was established.12 It was later found to be a present in virtually every vertebrate tissue, the highest concentrations occurring in the vitreous of the eye, in the synovial fluid in the joint capsule, and in the umbilical cord as Wharton s jelly. However, over 50% of total body HA is present in skin.13... 

Karl Meyer was a physician and biochemist who emigrated firom Hitler s Germany to America and worked at that time in the Eye Institute of the College of Physicians and Surgeons, Columbia University, in New York. He did not discover hyaluronic acid, which was known under the name of mucoitin sulfate, but he verified its chemical structure and discovered that it contained no sulfur. But, most importantly, he gave a new, more appropriate name to it hyaluronic acid. After reading his papers, I concluded... 

There are many kinds of natural biodegradable polymers. They are classified into three types according to their chemical structures, i.e., polysaccharides, polypeptides/proteins and polynucleotides/nucleic acids. Among them, polysaccharides, such as cellulose, chitin/chitosan, hyaluronic acid and starch, and proteins, such as silk, wool, poly( y-glutamic acid), and poly(e-lysin), are well known and particularly important industrial polymeric materials. 

In order to shed more light on the Interaction of water with these mucopolysaccharides, we employ the DSC method to follow the melting behavior of aqueous solutions of the polysaccharides cooled to -50 C. The polymers chosen here are chondroitin sulfate A (Chn S-A), chondroitin sulfate C (Chn S-C), chondroitin (Chn), heparin (Hpn), and hyaluronic acid (HyA). Their chemical structures are shown in Figure 1. The DSC curves allow us to determine the amount of the non-freezing water In highly concentrated solutions, since any endothermic peak Is not observed for such solutions over a wide temperature range (17. 18). This paper will also describe the presence of more than one endothermic peak In the DSC curves for solutions of relatively low polymer concentrations. 

Figure 6.6 Chemical composition of the dermatan sulfate and structure of aggregan complexes, (a) Chemical structure of repeated disaccharide of the GAG dermatan sulfate (protons are not indicated in this schematic diagram), (b) Schematic diagram of the aggregan proteoglycan complex showing the relationship between the core and linker proteins, GAGs, and hyaluronic acid).

As stated above, hyaluronic acid (Figure 1.1), also called hyaluronan and sometimes presented as a hyaluronate (poly)anion from the chemical/structural viewpoint, is a non-sulfated GAG, while all other glycosaminoglycans are sulfated polysaccharides (cf. Table 1.1). Another fundamental and remarkable difference between HA and the other GAGs is the mean molar mass of the native biopolymeric chains. While the value of several MDa is the most common one for HA synthesized by hyaluronan synthases (HASl, HAS2, and HASS), the molar mass of further glycosaminoglycans, on average, does not exceed the value of 50 kDa [8]. 

FIGURE 53.5 Chemical structure of hyaluronic acid, where n is the number of monomers present in the polymer. 

Fig. 21. Chemical structure formula of the hyaluronic acid, consisting of a repetitive basic unit made up by /1-D-glucuronic acid (1) and N-acetyl-/ -D-galactosamine (2). The glycosidic bonds are alternating p 1-3 and p 1-4 bonded. The molecular formula of the linear polymeric sodium hyaluronic acid reads as follows (Ci4H2oNNaOn)n...

Mengher LS, Pandher KS, Bron AJ, Davey CC. Effect of sodium hyaluronate (0.1%) on break-up time (NIBUT) in patients with dry eyes. Br J Ophthalmol 1986 70 442-447 Meyer DR, McCulley JP. Different prospects of risk management from in vitro toxicology and its relevance to the evolution of viscoelastic formulations. Rosen ES (ed) Viscoealstic Materials Basic Science and Clinical Applications. New York, Pergamon Press, 1989, S. 45-90 Meyer K, Palmer JW. The polysaccharide of the vitreous humor. J Biol Chem 1934 107 629-634 Meyer K. Chemical structure of hyaluronic acid. Fed Proc 1958 17 1075-1077... 

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