Aggregation of sodium dodecyl sulfate in micellar solution of beta-casein analyzed by 1H NMR self-diffusion, relaxation and Fourier transform IR spectroscopy

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Tissue-Specific Rhamnogalacturonan I Forms the Gel with Hyperelastic Properties

Plant cell wall is the source of the great number of carbohydrate structures that are built mainly on the base of ten types of polysaccharide backbones. The diversity of cell wall polysaccharides, including polysaccharides with the same type of backbone apparently correlates with their "functional fitting" Pectins including polygalacturonic acid and rhamnogalacturonan I and II take a key place among the well-characterized gel-forming polysaccharides of higher plants. The ability of pectin to form gel is mainly related with the presence of high-and low-methoxylated polygalacturonic acid in their structure , is located at the surface, and the neutral galactan chains, interacting with each ISSN 0006-2979, Biochemistry (Moscow), 2015, Vol. 80, No. 7, pp. 915-924. © Pleiades Publishing, Ltd., 2015. Published in Russian in Biokhimiya, 2015, Vol. 80, No. 7, pp. 1088-1098 915 Abbreviations: RGf, flax fiber rhamnogalacturonan I before incorporation into the cell wall; RGfcw, rhamnogalacturonan I of flax fiber cell wall; RGp, rhamnogalacturonan I of potato primary cell wall; RH, relative humidity. * To whom correspondence should be addressed. Abstract-Rhamnogalacturonans I are complex pectin polysaccharides extremely variable in structure and properties and widely represented in various sources. The complexity and diversity of the structure of rhamnogalacturonans I are the reasons for the limited information about the properties and supramolecular organization of these polysaccharides, including the relationship between these parameters and the functions of rhamnogalacturonans I in plant cells. In the present work, on the example of rhamnogalacturonan I from flax gelatinous fibers, the ability of this type of pectic polysaccharides to form at physiological concentrations hydrogels with hyperelastic properties was revealed for the first time. According to IR spectroscopy, water molecules are more tightly retained in the gelling rhamnogalacturonan I from flax fiber cell wall in comparison with the non-gelling rhamnogalacturonan I from primary cell wall of potato. With increase in strength of water binding by rhamnogalacturonan I, there is an increase in elastic modulus and decrease in Poisson's ratio of gel formed by this polysaccharide. The model of hyperelastic rhamnogalacturonan I capture by laterally interacting cellulose microfibrils, constructed using the finite element method, confirmed the suitability of rhamnogalacturonan I gel with the established properties for the function in the gelatinous cell wall, allowing consideration of this tissue-and stage-specific pectic polysaccharide as an important factor in creation of gelatinous fiber contractility. Tissue-Specific Rhamnogalacturona

Chitosan Graft Copolymers with <i>N</i>-Vinylimidazole as Promising Matrices for Immobilization of Bromelain, Ficin, and Papain

This work aims to synthesize graft copolymers of chitosan and N-vinylimidazole (VI) with different compositions to be used as matrices for the immobilization of cysteine proteases—bromelain, ficin, and papain. The copolymers are synthesized by free radical solution copolymerization with a potassium persulfate-sodium metabisulfite blend initiator. The copolymers have a relatively high frequency of grafting and yields. All the synthesized graft copolymers are water-soluble, and their solutions are characterized by DLS and laser Doppler microelectrophoresis. The copolymers are self-assembled in aqueous solutions, and they have a cationic nature and pH-sensitivity correlating to the VI content. The FTIR data demonstrate that synthesized graft copolymers conjugate cysteine proteases. The synthesized copolymer adsorbs more enzyme macromolecules compared to non-modified chitosan with the same molecular weight. The proteolytic activity of the immobilized enzymes is increased up to 100% compared to native ones. The immobilized ficin retains up to 97% of the initial activity after a one-day incubation, the immobilized bromelain retains 69% of activity after a 3-day incubation, and the immobilized papain retains 57% of the initial activity after a 7-day incubation. Therefore, the synthesized copolymers can be used as matrices for the immobilization of bromelain, ficin, and papain

Carboxymethyl Cellulose-Based Polymers as Promising Matrices for Ficin Immobilization

The present work is devoted to research on the interaction between carboxymethyl cellulose sodium salt and its derivatives (graft copolymer of carboxymethyl cellulose sodium salt and N,N-dimethyl aminoethyl methacrylate) with cysteine protease (ficin). The interaction was studied by FTIR and by flexible molecular docking, which have shown the conjugates&rsquo; formation with both matrices. The proteolytic activity assay performed with azocasein demonstrated that the specific activities of all immobilized ficin samples are higher in comparison with those of the native enzyme. This is due to the modulation of the conformation of ficin globule and of the enzyme active site by weak physical interactions involving catalytically valuable amino acids. The results obtained can extend the practical use of ficin in biomedicine and biotechnology