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Hyaluronic Acid (Hyaluronan): Pharmaceutical Applications
Published in Amit Kumar Nayak, Md Saquib Hasnain, Dilipkumar Pal, Natural Polymers for Pharmaceutical Applications, 2019
Amit Kumar Nayak, Mohammed Tahir Ansari, Dilipkumar Pal, Md Saquib Hasnain
Hyaluronate, a salt form of HA is found in human. It is predominantly present in soft connective tissues, such as umbilical cord, skin synovial fluid, and vitreous humor. Substantial concentrations of HA as hyaluronate are also present in the brain, lung, muscle tissues, and kidney (Brown and Jones, 2005). It is understood that the cellular synthesis of HA is a unique and highly controlled process, which is primarily located in Golgi bodies (Necas et al., 2008). The synthesis of HA is catalyzed by an enzyme hyaluronan synthases (HAS). HAS are classified as integral membrane proteins. Integral membrane proteins are found mostly embedded or associated in the cell membrane or plasma membrane. HAS have been classified as HAS1, HAS2, and HAS3 in vertebrates (Garg and Hales, 2004; Lee and Spicer, 2000). The function of HAS enzymes is to synthesize linear and long polymers of hyaluronan, a disaccharide structure with an addition of glucuronic acid and N-acetyl glucosamine (Necas et al., 2008).
Physical properties of the body fluids and the cell membrane
Published in Ronald L. Fournier, Basic Transport Phenomena in Biomedical Engineering, 2017
Protein molecules associated with the cell membrane can be classified into two broad categories. The transmembrane proteins are also amphipathic and extend through the lipid bilayer. They typically have hydrophobic regions that may travel across the membrane several times and hydrophilic ends that are exposed to water on either side of the membrane. Integral membrane proteins are transmembrane proteins that are held tightly within the cell membrane through chemical linkages with other components of the cell membrane. Integral proteins have major functions related to the transport of water-soluble but lipid-insoluble substances across the cell membrane. The peripheral membrane proteins are not located within the plasma membrane but associate on either side of the membrane with transmembrane or integral proteins. Peripheral proteins mostly function as enzymes.
Lipid–protein electrostatic interactions in the regulation of membrane–protein activities
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
Natalia Wilke, María B. Decca, Guillermo G. Montich
Electrostatic interactions regulate the activity of peripheral and amphitropic proteins mainly by changing the membrane–protein affinity, switching the protein between bound and unbound states, placing the protein in defined orientations, and helping enzymes to interact with substrates in the membrane. The location and orientation of integral membrane proteins is instead almost completely defined by the arrangement of hydrophobic transmembrane domains and hydrophilic anchor domains, with large energy barriers for changing global orientations. The control of functions of transmembrane proteins by electrostatic tools in the cell relies on stabilizing particular conformations that are coupled to changes in charge separation and movements of charges within the protein.
Formation of planar hybrid lipid/polymer membranes anchored to an S-layer protein lattice by vesicle binding and rupture
Published in Soft Materials, 2020
Christian Czernohlavek, Bernhard Schuster
There are significant efforts to design synthetic membranes as mimics of biomembranes.[1] The building blocks of bio-inspired systems constitute unique, predictable and tunable properties, diversity, and the possibility to fabricate ultrathin two-dimensional structures in the square-micrometer range with an astonishing variety of functionalities at the nanoscale.[2–7] Moreover, these natural building blocks like, e.g., lipids, proteins, and polymers self-assemble spontaneously into supramolecular structures.[8–10] One of the most important template for bio-inspired architectures is the cell envelope structure of prokaryotes, which is a complex layered structure comprising of a cell membrane and in many cases of a monomolecular array of protein subunits forming the outermost surface layer (S-layer).[4,9,11,12] The importance of cell membranes in biological systems as a barrier, preserver of the physical integrity of the cell and host for integral membrane proteins has prompted the development of membrane platforms that recapitulate fundamental aspects of membrane biology, especially the lipid bilayer environment.[7,13,14] This environment is of utmost importance for integral membrane proteins like channels, proton pumps, and (G protein-coupled) receptors, which are responsible for carrying out important specific membrane functions.[15–19]