Functionalized gluconamides and their metal complexes are shown to give supramolecular assemblies, in some cases chiral, and to form organogels in a large variety of organic solvents, e.g. methacrylate mixtures which can be poly merized, as well as o-xylene, chloroform, ethyl acetate, ethanol and tetrahydrofuran.

Four 12.2-12.6 kDa small heat-shock proteins (sHSPs) of Caenorhabditis elegans are the smallest known members of the sHSP family. They essentially comprise the characteristic C-terminal 'ct-crystallin domain' of the sHSPs, having a very short N-terminal region, and lacking a C-terminal tail. Recombinant Hspl2.2 and 12.3 are characterized here. Far-UV CD spectra reveal, as for other sHSPs, predominantly a [~-sheet structure. By gel permeation and crosslinking, they are the first sHSPs shown to occur as tetramers, rather than forming the usual large multimeric complexes. Exceptionally, too, both appear devoid of in vitro chaperone-like abilities. This supports the notion that tetramers are the building blocks of sHSP complexes, and that higher multimer formation, mediated through the N-terminal domains, is a prerequisite for chaperone-like activity.

SummaryThe oxidation of methionine residues in proteins to methionine sulfoxides occurs frequently and protein repair by reduction of the methionine sulfoxides is mediated by an enzyme, peptide methionine sulfoxide reductase (PMSR, EC 1.8.4.6), universally present in the genomes of all so far sequenced organisms. Recently, ®ve PMSR-like genes were identi®ed in Arabidopsis thaliana, including one plastidic isoform, chloroplast localised plastidial peptide methionine sulfoxide reductase (pPMSR) that was chloroplast-localized and highly expressed in actively photosynthesizing tissue (Sadanandom A et al., 2000). However, no endogenous substrate to the pPMSR was identi®ed. Here we report that a set of highly conserved methionine residues in Hsp21, a chloroplast-localized small heat shock protein, can become sulfoxidized and thereafter reduced back to methionines by this pPMSR. The pPMSR activity was evaluated using recombinantly expressed pPMSR and Hsp21 from Arabidopsis thaliana and a direct detection of methionine sulfoxides in Hsp21 by mass spectrometry. The pPMSR-catalyzed reduction of Hsp21 methionine sulfoxides occurred on a minute time-scale, was ultimately DTT-dependent and led to recovery of Hsp21 conformation and chaperone-like activity, both of which are lost upon methionine sulfoxidation (Ha È rndahl et al., 2001). These data indicate that one important function of pPMSR may be to prevent inactivation of Hsp21 by methionine sulfoxidation, since small heat shock proteins are crucial for cellular resistance to oxidative stress.

No abstract

High protein titers are gaining importance in biopharmaceutical industry. A major challenge in the development of highly concentrated mAb solutions is their long-term stability and often incalculable viscosity. The complexity of the molecule itself, as well as the various molecular interactions, make it difficult to describe their solution behavior. To study the formulation stability, long- and short-range interactions and the formation of complex network structures have to be taken into account. For a better understanding of highly concentrated solutions, we combined established and novel analytical tools to characterize the effect of solution properties on the stability of highly concentrated mAb formulations. In this study, monoclonal antibody solutions in a concentration range of 50–200 mg/ml at pH 5–9 with and without glycine, PEG4000, and Na2SO4 were analyzed. To determine the monomer content, analytical size-exclusion chromatography runs were performed. ζ-potential measurements were conducted to analyze the electrophoretic properties in different solutions. The melting and aggregation temperatures were determined with the help of fluorescence and static light scattering measurements. Additionally, rheological measurements were conducted to study the solution viscosity and viscoelastic behavior of the mAb solutions. The so-determined analytical parameters were scored and merged in an analytical toolbox. The resulting scoring was then successfully correlated with long-term storage (40 d of incubation) experiments. Our results indicate that the sensitivity of complex rheological measurements, in combination with the applied techniques, allows reliable statements to be made with respect to the effect of solution properties, such as protein concentration, ionic strength, and pH shift, on the strength of protein-protein interaction and solution colloidal stability.