Proteins and antibodies in serum, plasma, and whole blood-size characterization using asymmetrical flow field-flow fractionation (AF4).

The analysis of aggregates of therapeutic proteins is crucial in order to ensure efficacy and patient safety. Typically, the analysis is performed in the finished formulation to ensure that aggregates are not present. An important question is, however, what happens to therapeutic proteins, with regard to oligomerization and aggregation, after they have been administrated (i.

SAXS and X-ray crystallography suggest an unfolding model for the GDP/GTP conformational switch of the small GTPase Arf6.

The small GTPases Arf1 and Arf6 have nonoverlapping functions in cellular traffic despite their very high sequence and structural resemblance. Notably, the exquisite isoform specificity of their guanine nucleotide exchange factors and their distinctive sensitivity to the drug brefeldin A cannot be explained by any straightforward structural model. Here we integrated structural and spectroscopic methods to address this issue using Δ13Arf6-GDP, a truncated mutant that mimics membrane-bound Arf6-GDP.

Compounds binding to the S2-S3 pockets of thrombin.

A set of compounds designed to bind to the S2-S3 pockets of thrombin was prepared. These compounds included examples with no interactions in the S1 pocket. Proline, a common P2 in many thrombin inhibitors, was combined with known P3 residues and P1 substituents of varying size and lipophilicity.

Cofactor dependent conformational switching of GTPases.

This theoretical work covers structural and biochemical aspects of nucleotide binding and GDP/GTP exchange of GTP hydrolases belonging to the family of small GTPases. Current models of GDP/GTP exchange regulation are often based on two specific assumptions. The first is that the conformation of a GTPase is switched by the exchange of the bound nucleotide from GDP to GTP or vice versa.

Folding of S6 structures with divergent amino acid composition: pathway flexibility within partly overlapping foldons.

Studies of circular permutants have demonstrated that the folding reaction of S6 from Thermus thermophilus (S6(T)) is malleable and responds in an ordered manner to changes of the sequence separation between interacting residues: the S6(T) permutants retain a common nucleation pattern in the form of a two-strand-helix motif that can be recruited from different parts of the structure. To further test the robustness of the two-strand-helix nucleus we have here determined the crystal structure and folding reaction of an evolutionary divergent S6 protein from the hyperthermophilic bacterium Aquifex aeolicus (S6(A)). Although the overall topology of S6(A) is very similar to that of S6(T) the architecture of the hydrophobic core is radically different by containing a large proportion of stacked Phe side-chains.

Crystal structure of a mutant elongation factor G trapped with a GTP analogue.

Elongation factor G (EF-G) is a G protein factor that catalyzes the translocation step in protein synthesis on the ribosome. Its GTP conformation in the absence of the ribosome is currently unknown. We present the structure of a mutant EF-G (T84A) in complex with the non-hydrolysable GTP analogue GDPNP.

Structural insights into fusidic acid resistance and sensitivity in EF-G.

Fusidic acid (FA) is a steroid antibiotic commonly used against Gram positive bacterial infections. It inhibits protein synthesis by stalling elongation factor G (EF-G) on the ribosome after translocation. A significant number of the mutations conferring strong FA resistance have been mapped at the interfaces between domains G, III and V of EF-G.