Detailed insight into the structure and composition of industrial (technical) lignins is needed to devise efficient thermal, bio- or chemocatalytic valorisation strategies. Six such technical lignins covering three main industrial pulping methods (Indulin AT Kraft, Protobind 1000 soda lignin and Alcell, poplar, spruce and wheat straw organosolv lignins) were comprehensively characterised by lignin composition analysis, FT-IR, pyrolysis-GC-MS, quantitative ³¹P and 2D HSQC NMR analysis and molar mass distribution by Size Exclusion Chromatography (SEC). A comparison of nine SEC methods, including the first analysis of lignins with commercial alkaline SEC columns, showed molar masses to vary considerably, allowing some recommendations to be made. The lignin molar mass decreased in the order: Indulin Kraft > soda P1000 > Alcell > OS-W ∼ OS-P ∼ OS-S, regardless of the SEC method chosen. Structural identification and quantification of aromatic units and inter-unit linkages indicated that all technical lignins, including the organosolv ones, have considerably been degraded and condensed by the pulping process. Importantly, low amounts of β- ether linkages were found compared to literature values for protolignin and lignins obtained by other, milder isolation processes. Stilbenes and ether furfural units could also be identified in some of the lignins. Taken together, the insights gained in the structure of the technical lignins, in particular, the low β-O-4 contents, carry implications for the design of lignin valorisation strategies including (catalytic) depolymerisation and material applications.

Interaction of regulatory DNA binding proteins with their target sites is usually preceded by binding to nonspecific DNA. This speeds up the search for the target site by several orders of magnitude. We report the solution structure and dynamics of the complex of a dimeric lac repressor DNA binding domain with nonspecific DNA. The same set of residues can switch roles from a purely electrostatic interaction with the DNA backbone in the nonspecific complex to a highly specific binding mode with the base pairs of the cognate operator sequence. The protein-DNA interface of the nonspecific complex is flexible on biologically relevant time scales that may assist in the rapid and efficient finding of the target site.

The three-dimensional structure of the DNA-binding domain (DBD) of the glucocorticoid receptor has been determined by nuclear magnetic resonance spectroscopy and distance geometry. The structure of a 71-residue protein fragment containing two "zinc finger" domains is based on a large set of proton-proton distances derived from nuclear Overhauser enhancement spectra, hydrogen bonds in previously identified secondary structure elements, and coordination of two zinc atoms by conserved cysteine residues. The DBD is found to consist of a globular body from which the finger regions extend. A model of the dimeric complex between the DBD and the glucocorticoid response element is proposed. The model is consistent with previous results indicating that specific amino acid residues of the DBD are involved in protein-DNA and protein-protein interactions.