China
Africa
Explore chapters and articles related to this topic
Protocols for Key Steps in the Development of an Immunoassay
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
Caroline Murphy, Richard O’Kennedy
The addition of low concentrations of salts can help to stabilise proteins [31]. Kosmotropic agents (their name derives from the word ‘kosmotrope’ (order-making)) function to stabilise proteins and hydrophobic aggregates in solution. They form strong hydrogen bonds and act to exclude hydrophobic residues (usually forming the internal structure of the protein) from the solvent, thereby maintaining the structural integrity of the protein. Too high a concentration of kosmotropic reagents will cause the protein to ‘salt out’. Therefore, a balance must be achieved. Chaotropic agents get their name from the word ‘chaotrope’ (disorder-making) and function to destabilise proteins. They break up hydrogen bonds and increase the solubility of proteins in aqueous solutions. This encourages the protein to denature. Amino acids: During the production of recombinant proteins, arginine can be used to enhance the amount of appropriately refolded proteins. Arginine, used at high concentrations (2M) has the capacity to suppress aggregation of partially folded intermediates [32].
Production, Purification, and Application of the Microbial Enzymes
Published in Pankaj Bhatt, Industrial Applications of Microbial Enzymes, 2023
Anupam Pandey, Ankita H. Tripathi, Priyanka H. Tripathi
Protein surface carries hydrophobic groups or clusters of hydrophobic groups, which contributes to their surface hydrophobicity that allows the interactions with other proteins as well as with the column carrying hydrophobic groups. Interaction with non-polar compounds in a polar environment is enhanced and gains entropy by liberating water molecules, which drives the clustering of the hydrophobic groups. The hydrophobic interactions are affected by altering the structure of water by dissolved salts. For example, kosmotropic salts enhance the strength of the hydrophobic interactions while chemotropic salts weaken it. The resins commonly used for HIC are substituted with n-butyl, n-octyl, or phenyl groups. For an uncharacterized protein, phenyl-substituted resin is usually preferred over the highly hydrophobic octyl-substituted resins. The phenyl ligand is moderately hydrophobic in comparison to n-butyl and n-pentyl and will bind to aromatic amino acids through π–π interactions. To purify a protein from a crude extract with an ammonium sulfate precipitation at a concentration of ammonium sulfate that leaves desired protein in solution and its precipitates by centrifugation. The clarified solution is used for HIC elutes by decreasing the level of kosmotropic salts in the buffer. The proteins are eluted based on their hydrophobicity, while those tightly bounded ones which are difficult to elute with negative gradient are eluted with a positive gradient of organic solvent (McCue, 2009). The most common methods for analyzing the final purity of the enzymes are sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), analytical gel filtration, and mass spectrometry (Rhodes and Laue, 2009).
Kosmotropic Chromatography of Proteins
Published in Nelu Grinberg, Peter W. Carr, Advances in Chromatography Volume 57, 2020
Carlos Calleja-Amador, J. F. Ogilvie, Rigoberto Blanco
Kosmotropic ions are supposed to induce local water structuring through hydration. This structuring depends on the size of the ions and on electrostatic and quantum-mechanical interactions. The short-range interactions involving the ionic species depend on van der Waals forces between the hydrated ions and the surfaces (due to the superposition of the hydration layers). The long-range electrostatic interactions depend on the nature of the solvent and its interaction with the molecules that might be present, such as proteins, other biomolecules and impurities (dissolved gases) [26,27].
Response surface methodology for optimisation of glycyrrhizic acid extraction from Glycyrrhiza glabra in the aqueous two-phase system
Published in Indian Chemical Engineer, 2023
Kavita J. Lanjekar, Virendra K. Rathod
In addition, due to ionic hydration, when dissolved in an aqueous solution, the ions of a kosmotropic salt, such as sodium citrate, are enclosed by a water molecules layer. The water molecules get structured in the presence of a kosmotropic salt; thus, its availability as a solvent is decreased to other molecules or ions. Therefore, in the present work, many water molecules can be involved in hydrating citrate ions, thereby altering the solubility of glycyrrhizic acid in an aqueous phase and pushing it to the PEG phase. As a result, when sodium citrate concentration was increased from 14% (w/v) to 19% (w/v), the yield of GA in the top PEG-rich phase increased from 17.76 mg/g to 28.44 mg/g GA. At 19% (w/v), a high yield of glycyrrhizic acid was obtained. However, at a high salt concentration of 24% (w/v), the yield was reduced to 24.02 mg/g GA. This might be due to the limited availability of water molecules for extracting GA from powder at a high salt concentration of 24% (w/v). Thus, a sodium citrate concentration of 19% (w/v) was found suitable for glycyrrhizic acid in ATPS. A similar trend was observed in a recent study to purify phycobiliproteins in cyanobacteria through PEG/Citrate ATPS with 14% sodium citrate concentration [39].