Hydrodynamic properties of protein solutions

Again, so long as one speaks qualitatively, it is well established that solute protein is hydrated in water solution (cf. D. Results from measurements of the hydrodynamic properties of protein solutions and the hydrodynamic properties of proteins molecules in solution, from the early work on viscosity, flow birefringence, and dielectric relaxation (cf. O to the more modem work on translational and rotational diffusion measured by inelastic... 

The hydrodynamic properties of protein solutions have consistently suggested that the apparent dimensions of the protein are larger than expected. They can be explained by assuming that there is a hydration shell of water that moves with the protein. The exact value of the size of the shell varies but calculations which take accoxmt of protein structure and electrostatie properties suggest values of around 0.4 g of water per g of protein are involved. These figures are remarkably similar to the amoimts of non-freezing water observed and therefore are suggestive of a real effect due to some kind of water with different properties. 

In a dilute protein solution, the nano length scale or the molecular structure of protein molecules determines the thermodynamic equilibrium between protein-protein and protein-water interactions. The consequent surface and hydrodynamic properties of proteins are resulted from the proportion of hydrophobic, hydrophilic, and charged amino acid residues. For example, caseins could adopt a random coil structure due to their flexible structure as a result of phosphorylated serine residues caseins indeed lack the ordered structures of a-helix, 3-sheet, and 3-turn found in globular proteins. This gives rise to better multifunctionality of caseins over globular proteins. 

Works where study the hydrodynamic properties of a biopolymers in aqueous solution at different temperatures are made by Guner (1999), and Guner Kibarer (2001) for dextran Ghen Tsaih (1998) and Kasaii (2008) for chitosan, Bohidar for gelatin (1998), and Monkos for serum proteins (1996,1997,1999, 2000, 2004 and 2005). 

This volume consists of four parts. The first part is devoted to theoretical studies and computer simulations. These studies deal with the structure and dynamics of polymers adsorbed at interfaces, equations of state for particles in polymer solutions, interactions in diblock copolymer micelles, and partitioning of biocolloidal particles in biphasic polymer solutions. The second part discusses experimental studies of polymers adsorbed at colloidal surfaces. These studies serve to elucidate the kinetics of polymer adsorption, the hydrodynamic properties of polymer-covered particles, and the configuration of the adsorbed chains. The third part deals with flocculation and stabilization of particles in adsorbing and nonadsorbing polymer solutions. Particular focus is placed on polyelectrolytes in adsorbing solutions, and on nonionic polymers in nonadsorbing solutions. In the final section of the book, the interactions of macromolecules with complex colloidal particles such as micelles, liposomes, and proteins are considered. 

DLS is an established technique for protein characterization. For example, to And optimum protein crystalhzation conditions, DLS is used as a prescreening tool to identify critical parameters of the process such as the hydrodynamic size, polydispersity, and aggregation factors. DLS is also used as a method to characterize the hydrodynamic properties of globular proteins in electrolyte solutions. However, applications of DLS to characterize charged protein solutions, just as any other charged molecules in solution, could face certain difficulties in subsequent data treatment. 

In 1958 we had reported that in contrast to most globular proteins, the specific optical rotation, [a], the hydrodynamic properties, and, most of all, the enzymic activity of pepsin remain unaltered if the protein is dissolved in concentrated urea solution or in guanidine hydrochloride, or if the solution is heated to 60°C. However, if the temperature is raised to 70°C., the rotatory dispersion constant, Xc, increases from 216 to 236 m/z (15, 18). Although hydrogen bonds of the type C = O. . . H — N and those involving the phenolic hydroxyls of tyrosine and the carboxylate ions of the acidic amino acid residues—i.e.,... 

---