The present paper demonstrates that both hardwoods and softwoods are readily soluble in various imidazolium-based ionic liquids (ILs) under gentle conditions. More specifically, a variety of ionic liquids can only partially dissolve wood chips, whereas ionic liquids such as 1-butyl-3-methylimidazolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical pulp (TMP) fibers. Despite the fact that the obtained solutions were not fully clear, these ionic liquids provided solutions which permitted the complete acetylation of the wood. Alternatively, transparent amber solutions of wood could be obtained when the dissolution of the same lignocellulosic samples was attempted in 1-benzyl-3-methylimidazolium chloride. This realization was based on a designed augmented interaction of the aromatic character of the cation of the ionic liquid with the lignin in the wood. After dissolution, wood can be regenerated as an amorphous mixture of its original components. The cellulose of the regenerated wood can be efficiently digested to glucose by a cellulase enzymatic hydrolysis treatment. Furthermore, completely acetylated wood was found to be readily soluble in chloroform, allowing, for the first time, detailed proton nuclear magnetic resonance (NMR) spectra and NMR diffusion measurements to be made. It was thus demonstrated that the dissolution of wood in ionic liquids now offers a variety of new possibilities for its structural and macromolecular characterization, without the prior isolation of its individual components. Furthermore, considering the relatively wide solubility and compatibility of ionic liquids with many organic or inorganic functional chemicals or polymers, it is envisaged that this research could create a variety of new strategies for converting abundant woody biomass to valuable biofuels, chemicals, and novel functional composite biomaterials.

A quantitative method to record (1)H-(13)C correlation NMR spectra (Q-HSQC) is presented. The suppression of (1)J(CH)-dependence is achieved by modulating the polarization transfer delays of HSQC. In addition, the effect of homonuclear couplings, as well as relaxation during the pulse sequence are discussed. We developed the Q-HSQC approach for the quantitative analysis of wood lignin, a complex polymer where it has been difficult to obtain reliable data on the relative amounts of different structural units. The current method is applicable to a variety of complex mixtures, where normal 1D (1)H- and (13)C-NMR methods fail.

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The ionic liquids 1-ethyl-3-methylimidazolium acetate [emim]OAc, N,N,N,N-tetramethylguanidium propionate [TMGH]EtCO(2), and N,N,N,N-tetramethylguanidium acetate [TMGH]OAc, and the traditional cellulose solvent N-methylmorpholine N-oxide NMMO were characterized for their Kamlet-Taft (KT) values at several water contents and temperatures. For the ionic liquids and NMMO, thresholds of regeneration of cellulose solutions by water were determined using nephelometry and rheometry. Regeneration from wet IL was found to be asymmetric compared to dissolution into wet IL. KT parameters were found to remain almost constant at temperatures, between 20-100 °C, even at different water contents. Among the KT parameters, the β value was found to change most drastically, with an almost linear decrease upon addition of water. The ability of the mixtures to dissolve cellulose was best explained by the difference β-α (net basicity), rather than β alone. Regeneration of cellulose starts at thresholds values of approximately β < 0.8 (β-α < 0.35) and displayed four phases.

The repertoire of secondary metabolism (involving the production of compounds not essential for growth) in the plant kingdom is enormous, but the genetic and functional basis for this diversity is hard to analyse as many of the biosynthetic enzymes are unknown. We have now identified a key enzyme in the ornamental plant Gerbera hybrida (Asteraceae) that participates in the biosynthesis of compounds that contribute to insect and pathogen resistance. Plants transformed with an antisense construct of gchs2, a complementary DNA encoding a previously unknown function, completely lack the pyrone derivatives gerberin and parasorboside. The recombinant plant protein catalyses the principal reaction in the biosynthesis of these derivatives GCHS2 is a polyketide synthase that uses acetyl-CoA and two condensation reactions with malonyl-CoA to form the pyrone backbone of the natural products. The enzyme also accepts benzoly-CoA to synthesize the backbone of substances that have become of interest as inhibitors of the HIV-1 protease. GCHS2 is related to chalcone synthase (CHS) and its properties define a new class of function in the protein superfamily. It appears that CHS-related enzymes are involved in the biosynthesis of a much larger range of plant products than was previously realized

Determination of molecular weight parameters of native and, in particular, technical lignins are based on size exclusion chromatography (SEC) approaches. However, no matter which approach is used, either conventional SEC with a refractive index detector and calibration with standards or multi‐angle light scattering (MALS) detection at 488 nm, 633 nm, 658 nm, or 690 nm, all variants can be severely erroneous. The lack of calibration standards with high structural similarity to lignin impairs the quality of the molar masses determined by conventional SEC, and the typical fluorescence of (technical) lignins renders the corresponding MALS data rather questionable. Application of MALS detection at 785 nm by using an infrared laser largely overcomes those problems and allows for a reliable and reproducible determination of the molar mass distributions of all types of lignins, which has been demonstrated in this study for various and structurally different analytes, such as kraft lignins, milled‐wood lignin, lignosulfonates, and biorefinery lignins. The topics of calibration, lignin fluorescence, and lignin UV absorption in connection with MALS detection are critically discussed in detail, and a reliable protocol is presented. Correction factors based on MALS measurements have been determined for commercially available calibration standards, such as pullulan and polystyrene sulfonate, so that now more reliable mass data can be obtained also if no MALS system is available and these conventional calibration standards have to be resorted to.

Filamin A (FLNa), a dimeric actin crosslinking and scaffold protein with numerous intracellular binding partners, anchors the platelet adhesion glycoprotein (GP) Ib-IX-V receptor to actin cytoskeleton. We mapped the GPIb␣ binding site to a single domain of FLNa and resolved the structure of this domain and its interaction complex with the corresponding GPIb␣ cytoplasmic domain. This is the first atomic structure of this class of membrane glycoprotein-cytoskeleton connection. GPIb␣ binds in a groove formed between the C and D ␤ strands of FLNa domain 17. The interaction is strikingly similar to that between the ␤7 integrin tail and a different FLNa domain, potentially defining a conserved motif for FLNa binding. Nevertheless, the structures also reveal specificity of the interfaces, which explains different regulatory mechanisms. To verify the topology of GPIb-FLNa interaction we also purified the native complex from platelets and showed that GPIb interacts with the C-terminus of FLNa, which is in accordance with our biochemical and structural data. (Blood. 2006;107:1925-1932

Different acid-base conjugates were made by combining a range of bases and superbases with acetic and propionic acid. Only the combinations that contained superbases were capable of dissolving cellulose. Proton affinities were calculated for the bases. A range, within which cellulose dissolution occurred, when combined with acetic or propionic acid, was defined for further use. This was above a proton affinity value of about 240 kcal mol(-1) at the MP2/6-311+G(d,p)//MP2/ 6-311+G(d,p) ab initio level. Understanding dissolution allowed us to determine that cation acidity contributed considerably to the ability of ionic liquids to dissolve cellulose and not just the basicity of the anion. By XRD analyses of suitable crystals, hydrogen bonding interactions between anion and cation were found to be the dominant interactions in the crystalline state. From determination of viscosities of these conjugates over a temperature range, certain structures were found to have as low a viscosity as 1-ethyl-3-methylimidazolium acetate, which was reflected in their high rate of cellulose dissolution but not necessarily the quantitative solubility of cellulose in those ionic liquids. 1,5-Diazabicyclo[4.3.0]non-5-enium propionate, which is one of the best structures for cellulose dissolution, was then distilled using laboratory equipment to demonstrate its recyclability.