Search results for "Biophysic"

Crystal structure of bacteriophage fr capsids at 3.5 A resolution.

1994

The structure of recombinant capsids of the bacterial virus fr has been determined by X-ray crystallography at 3.5 A resolution. The capsids were produced by expressing the fr coat protein in Escherichia coli, the natural host of the virus, and are probably essentially identical to the protein shell of the native virus. The structure was determined using molecular replacement with the protein shell of the related MS2 virus, and refined to a crystallographic R-factor of 0.228. A comparison of the protein shells of the viruses shows that they are very similar, and indicates that they may have a similar regulation of the assembly of the quasi-symmetrical protein shell.

Hydrophilicity Regulates the Stealth Properties of Polyphosphoester‐Coated Nanocarriers

2018

Increasing the plasma half-life is an important goal in the development of drug carriers, and can be effectively achieved through the attachment of polymers, in particular poly(ethylene glycol) (PEG). While the increased plasma half-life has been suggested to be a result of decreased overall protein adsorption on the hydrophilic surface in combination with the adsorption of specific proteins, the molecular reasons for the success of PEG and other hydrophilic polymers are still widely unknown. We prepared polyphosphoester-coated nanocarriers with defined hydrophilicity to control the stealth properties of the polymer shell. We found that the log P value of the copolymer controls the composit…

Conformational changes involved in thermal aggregation processes of bovine serum albumin

2003

We report a kinetic study on thermal aggregation process of the model protein bovine serum albumin (BSA) in low concentration regime. Aim of this study is to provide information on relationship between conformational changes and initial step of aggregation. The experimental approach is based on steady-state fluorescence spectra of the two tryptophans located in two different domains, in way to study conformational changes in the surrounding of these residues. We also follow emission spectra of Fluorescein-5-Maleimide dye bound to the single free cysteine of BSA. Complementary information on the extent of aggregation and on the structural changes is obtained by Rayleigh scattering and circul…

Thermal aggregation of beta-lactoglobulin in presence of metal ions.

2007

In this work, we report a study of the effects of zinc and copper ions on the heat-induced aggregation of beta-lactoglobulin (BLG). Kinetics investigations on aggregates growth by light scattering measurements and on secondary structure changes by FTIR absorption measurements show the different role played by the two metals during the whole process. In particular, the presence of zinc in solution promotes the formation of aggregates of BLG at a lower temperature than copper. Then, at fixed temperature, formation of a large amount of aggregates, of large dimension, is observed for Zn-BLG in shorter time; on the contrary, the presence of copper in solution does not affect the aggregation proc…

Thin-layer affinity chromatography in analysis of protein-ligand affinity.

1996

A reduction of protein specific motions in co-ligated myoglobin embedded in a trehalose glass

2000

Denaturation via Surfactants Changes Composition of Protein Corona

2018

The use of nanocarriers as drug delivery vehicles brings them into contact with blood plasma proteins. Polymeric nanocarriers require some sort of surfactant to ensure colloidal stability. Formation of the protein corona is therefore determined not only by the intrinsic properties of the nanocarrier itself but also by the accompanying surfactant. Although it is well-known that surfactants have an impact on protein structure, only few studies were conducted on the specific effect of surfactants on the composition of protein corona of nanocarriers. Therefore, we analyzed the composition of the protein corona on "stealth" nanoparticles with additional surfactant (cetyltrimethylammonium chlorid…

Methodological approaches for the analysis of transmembrane domain interactions: A systematic review

2021

The study of protein-protein interactions (PPI) has proven fundamental for the understanding of the most relevant cell processes. Any protein domain can participate in PPI, including transmembrane (TM) segments that can establish interactions with other TM domains (TMDs). However, the hydrophobic nature of TMDs and the environment they occupy complicates the study of intramembrane PPI, which demands the use of specific approaches and techniques. In this review, we will explore some of the strategies available to study intramembrane PPI in vitro, in vivo, and, in silico, focusing on those techniques that could be carried out in a standard molecular biology laboratory regarding its previous e…

Metal coordination of azurin in the unfolded state.

1998

Abstract1H NMR data applied to the paramagnetic cobalt(II) derivative of azurin from Pseudomonas aeruginosa have made it possible to show that the metal ion is bound to the protein in the unfolded state. The relaxation data as well as the low magnetic anisotropy of the metal ion indicate that the cobalt ion is tetrahedral in the unfolded form. The cobalt ligands have been identified as the residues Gly45, His46, Cys112 and His117. Met121 is not coordinated in the unfolded state. In this state, the metal ion is not constrained to adopt a bipyramidal geometry, as imposed by the protein when it is folded. This is clear confirmation of the rack-induced bonding mechanism previously proposed for …

Folding energetics and oligomerization of polytopic α-helical transmembrane proteins

2014

While interactions of single-span transmembrane helices have been studied to a significant extent in the past years, the folding of polytopic α-helical transmembrane proteins as well as their oligomerization, are far less analyzed and understood. The goal of the few thus far performed thermodynamic studies, in which unfolding of polytopic TM proteins was described, was to achieve a mild, potentially reversible unfolding process, to finally derive thermodynamic parameters for the reverse folding pathway. In the first part of this review, we summarize the studies analyzing the thermodynamic stability and folding pathways of polytopic transmembrane proteins. Based on these studies, we deduce s…