Plant-Based Cellulase Assay Systems as Alternatives for Synthetic Substrates.

Dissociative enzymes such as cellulases are greatly desired for a variety of applications in the food, fuel, and fiber industries. Cellulases and other cell wall-degrading enzymes are currently being engineered with improved traits for application in the breakdown of lignocellulosic biomass. Biochemical assays using these "designer" enzymes have traditionally been carried out using synthetic substrates such as crystalline bacterial microcellulose (BMCC). However, the use of synthetic substrates may not reflect the actual action of these cellulases on real plant biomass. We examined the potential of suspension cell walls from several plant species as possible alternatives for synthetic cellulose substrates. Suspension cells grow synchronously; hence, their cell walls are more uniform than those derived from mature plants. This work will help to establish a new assay system that is more genuine than using synthetic substrates. In addition to this, we have demonstrated that it is feasible to produce cellulases inexpensively and at high concentrations and activities in plants using a recombinant plant virus expression system. Our long-term goals are to use this system to develop tailored cocktails of cellulases that have been engineered to function optimally for specific tasks (i.e., the conversion of biomass into biofuel or the enhancement of nutrients available in livestock feed). The broad impact would be to provide a facile and economic system for generating industrial enzymes that offer green solutions to valorize biomass in industrialized communities and specifically in developing countries.

Fungal Enzymes for Bio-Products from Sustainable and Waste Biomass.

Lignocellulose, the most abundant renewable carbon source on earth, is the logical candidate to replace fossil carbon as the major biofuel raw material. Nevertheless, the technologies needed to convert lignocellulose into soluble products that can then be utilized by the chemical or fuel industries face several challenges. Enzymatic hydrolysis is of major importance, and we review the progress made in fungal enzyme technology over the past few years with major emphasis on (i) the enzymes needed for the conversion of polysaccharides (cellulose and hemicellulose) into soluble products, (ii) the potential uses of lignin degradation products, and (iii) current progress and bottlenecks for the use of the soluble lignocellulose derivatives in emerging biorefineries.

On and off-target effects of telomere uncapping G-quadruplex selective ligands based on pentacyclic acridinium salts.

Quadruplexes DNA are present in telomeric DNA as well as in several cancer-related gene promoters and hence affect gene expression and subsequent biological processes. The conformations of G4 provide selective recognition sites for small molecules and thus these structures have become important drug-design targets for cancer treatment. The DNA G-quadruplex binding pentacyclic acridinium salt RHPS4 (1) has many pharmacological attributes of an ideal telomere-targeting agent but has undesirable off-target liabilities. Notably a cardiovascular effect was evident in a guinea pig model, manifested by a marked and sustained increase in QTcB interval. In accordance with this, significant interaction with the human recombinant ß2 adrenergic receptor, and M1, M2 and M3 muscarinic receptors was observed, together with a high inhibition of the hERG tail current tested in a patch clamp assay. Two related pentacyclic structures, the acetylamines (2) and (3), both show a modest interaction with ß2 adrenergic receptor, and do not significatively inhibit the hERG tail current while demonstrating potent telomere on-target properties comparing closely with 1. Of the two isomers, the 2-acetyl-aminopentacycle (2) more closely mimics the overall biological profile of 1 and this information will be used to guide further synthetic efforts to identify novel variants of this chemotype, to maximize on-target and minimize off-target activities. Consequently, the improvement of toxicological profile of these compounds could therefore lead to the obtainment of suitable molecules for clinical development offering new pharmacological strategies in cancer treatment.