Temperature and salt controlled tuning of protein clusters

Abstract

The formation of molecular assemblies in protein solutions is of strong interest both from a fundamental viewpoint and for biomedical applications. While ordered and desired protein assemblies are indispensable for...

Notes on Fitting and Analysis Frameworks for QENS Spectra of (Soft) Colloid Suspensions

“…Since several parameters, such as the parametrization of the resolution or the solvent contribution depend on q, a global fit needs to have q-dependent fixed parameters, as well as q-independent and q-dependent fit parameters. In the event that not only one single spectrum, but several spectra are analyzed simultaneously, e.g., to extract temperature independent entropy and enthalpy values instead of free energies [24], the complexity of the model increases even further, since the background signal dominated by the solvent is also temperature dependent.…”

“…By investigating the different contributions, it becomes visible that especially in the case of non-symmetrical resolution functions, it is important to consider the additional contributions. It should be mentioned that the internal diffusive processes are better accounted for by two coupled Lorentzian functions describing the motion of the protein backbone and side chains individually [22,24]. For reasons of comparability, the same model is applied for the different energy ranges.…”

Short-Time Transport Properties of Bidisperse Suspensions of Immunoglobulins and Serum Albumins Consistent with a Colloid Physics Picture

“…For the time and length-scale investigated, it can be described by a Fickian diffusion process, which translates into a Lorentzian function with the width γ( q ) = Dq 2 . 40 , 45 , 51 , 53 , 54 In the energy transfer range investigated, the internal diffusive contribution of the proteins can also be described by a Lorentzian function. 45 , 51 The incoherent scattering signal can thus be approximated by …”

“…Previous studies investigated the dependence of the apparent short-time center-of-mass diffusion coefficients on the protein volume fraction for several proteins in single-component solutions. ,, For different globular proteins, an apparent diffusion coefficient D = D ( D r , D t ), consisting of the translational D t and rotational D r diffusion, has been observed for significantly changing environments. For the time and length-scale investigated, it can be described by a Fickian diffusion process, which translates into a Lorentzian function with the width γ­( q ) = Dq 2 . ,,,, In the energy transfer range investigated, the internal diffusive contribution of the proteins can also be described by a Lorentzian function. , The incoherent scattering signal can thus be approximated by …”

“…with and describing the apparent global diffusion and the internal diffusive processes, respectively. Although this approach is developed for the monodisperse system, several studies have shown that it can be applied to cluster forming systems. , In this case, eq is averaging, on the one hand, over the different global diffusive dynamics of the two proteins and, on the other hand, over their internal dynamics.…”