PubMed · 5409543
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R G Spiro. 1970-01-15. Protein-hyaluronate linkage.. https://doi.org/10.1056/nejm197001152820314
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The rheological properties of the sulfated polysaccharide of the red microalga Porphyridium sp., a heteropolymer with a molecular weight of 3-5 x 10(6) Da, indicated that this material might be an excellent candidate for lubrication applications: the viscosity of the polysaccharide is stable over a range of temperatures, pH values, and salinities. In this study, various rheological and lubricant properties of the polysaccharide were evaluated in comparison with those of a widely used biolubricant, hyaluronic acid. The viscosity of the Porphyridium sp. polysaccharide remained essentially unchanged in a temperature range of 25-70 degrees C. In tribology tests on a ball-on-flat ceramic pair, the values for the friction coefficient and wear rate for the pair lubricated with polysaccharide were remarkably lower than those for hyaluronic acid, especially at high loads. In a test on a steel ring/ultrahigh-molecular-weight polyethylene (UHMWPE) block pair, the wear tracks on the surface of the UHMWPE were more pronounced for hyaluronic acid than for the polysaccharide. Atomic force microscopy showed that the polysaccharide was effectively adsorbed onto mica surfaces, forming ultrathin coating layers in the nanometer range. As is required for biolubricant applications, the polysaccharide was not degraded by hyaluronidase. The stability of the Porphyridium sp. polysaccharide to heat and to hyaluronidase combined with its ability to reduce friction and wear indicate its potential as an advantageous biolubricant.
The giant polyelectrolyte glycosaminoglycan hyaluronan (1-10 MDa) is a major component of the pericellular coat on a variety of cells, where it is an important modulator and mediator of early cell adhesion events. This pericellular layer can reach 5 mum thickness on cells that produce cartilage (chondrocytes), and up to 2 mum on Xenopus laevis kidney epithelial cells (A6). We are interested in generating model systems for the pericellular coat in order to learn more about the structure and function of hyaluronan on biological or artificial surfaces. We report here the synthesis of model systems where a coat of coordinatively cross-linked hyaluronan of up to 2 mum thickness was covalently photografted onto polystyrene microspheres. The hydrated coat was imaged directly by environmental scanning electron microscopy (ESEM) at close to 100% relative humidity. The key feature of the procedure is the reversible reverse-temperature phase transition of hyaluronan induced by trivalent lanthanide cations, which is exploited to achieve sufficient density for grafting of thick layers. The microsphere-grafted coat shows a temperature-dependent swelling when labeled with lanthanide ions (Gd(3+) or Tb(3+)). We directly observed a volume contraction of 20% with increasing temperature between 1 and 11 degrees C by wet-mode ESEM.
In the current work, the molecular recognition and interaction were studied by taking advantages of the environmentally sensitive fluorescence of hypocrellin B (HB) and the structural knowledge of hyaluronan (HYA), a polysaccharide over-expressed in tumor cells or tissues. Interestingly, it was found that, binding to HYA, the absorbance of HB would be greatly strengthened, suggesting HB fitting to a hydrophobic environment in HYA, while the fluorescence seriously quenched at pH 7.0, which was very distinct from the binding of HB to proteins, liposome, other polysaccharide molecules or HYA at pH 2.0. Synchronously, the particle size of HYA would become bigger after interaction with HB, suggesting an aggregation of HYA. Considering the spectral responses of HB and the particle size change of HYA, a specific interaction of HB with HYA was proposed, that is, an HB molecule would link two HYA molecules not only by hydrophobic interaction but also by formations of intermolecular hydrogen bonds at physiological pH values. Furthermore, the estimated binding constant suggests a quite high affinity of HB to HYA. Besides, an oxygen-dependent degradation of HYA and photobleaching of HB were observed via photosensitization of HB.