Viscosity of protein

Surface shear rheology at the oil-water interface is a sensitive probe of protein-polysaccharide interactions. In particular, there is considerable experimental evidence for a general increase in surface shear viscosity of protein adsorbed layers as a result of interfacial complexation with polysaccharides (Dickinson et al., 1998 Dickinson and Euston, 1991 Dickinson and Galazka, 1992 Semenova et al., 1999a Jourdain et al., 2009). One such example is the case of asi-casein + pectin at pH = 5.5 and ionic strength = 0.01 M (Ay = - 334 x 10 cm /mol) the interfacial viscosity after 24 hours was found to be five times larger in the presence of pectin (i.e., values of 820 80 and 160 20 mN m 1 with and without pectin, respectively) (Semenova et al., 1999a). 

Figure 10. Influence of cholesterol on the surface viscosity of protein films adsorbed from 0.15M NaCl at 25° C. Protein BSA ( ) 10 fig/ml, RNase (O) 10 ng/ml. At 40 min, microliter quantities of lipid-DPL or cholesterol [J i g/id in chloroform-methanol (85 15)] were added on the protein film. The solvent alone did not affect either surface pressure or viscosity.

Multiple regression analysis performed for succinylated rapeseed protein isolates indicated that emulsification activity was related to protein solubility, hydrophobicity, zeta potential, and flow behavior of aqueous dispersions of the proteins. Emulsion stability was affected by protein solubility, zeta potential, apparent viscosity of protein dispersions, and difference in density between aqueous and oil phases [76],... 

Protein charges that maintain the folded structure will be neutralized the electrostatic mteraction with guanidine chloride inducing by that an unfolded protein Also, mteraction occurs with the amino acids of the inner core of the protein inducing by that an irreversible unfolded state in presence of the denaturant. Equation 1.13 gives the relation that exists between the intrinsic viscosity of proteins (p) in presence nf 6 M guanidine chloride and the number (n) of amino acid residues per protein chain (Tanford elal. 1967). 

Surface Viscosity of Protein Monolayers. Figure 2 shows the surface viscosity ( H g) of a number of proteins and one polyamino acid as a function of H ( ), The extremely high surface viscoelasticity of protein monolayers appears to be more characteristic of an interacting random chain system than an array of rigid helices. The theory of surface viscosity of Moore and Eyring ), based on the Theory of Absolute Reaction Rates, postulates that the flow of a monolayer consists of movements of flow units, normally molecules, from one equilibrium position to another, over an intermediate activation energy barrier. The equation derived for the coefficient of surface viscosity ( g)... 

Hahn, D. K., and Aragon, S. R., Intrinsic viscosity of proteins and platonic solids by boundary element methods, J. Chem. Theory Comput, 2, 1416-1428 (2006). 

Effect of Intrachain Disulfide Bonds on Intrinsic Viscosities of Proteins in Concentrated Guanidine Hydrochloride (GuHCl) Solutions"... 

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