AibA/AibB Induces an Intramolecular Decarboxylation in Isovalerate Biosynthesis by Myxococcus xanthus

Isovaleryl coenzyme A (IV‐CoA) is an important precursor for iso ‐fatty acids and lipids. It acts in the development of myxobacteria, which can produce this compound from acetyl‐CoA through alternative IV‐CoA biosynthesis (aib). A central reaction of aib is catalyzed by AibA/AibB, which acts as a cofactor‐free decarboxylase despite belonging to the family of CoA‐transferases. We developed an efficient expression system for AibA/AibB that allowed the determination of high‐resolution crystal structures in complex with different ligands. Through mutational studies, we show that an active‐site cysteine previously proposed to be involved in decarboxylation is not required for activity. Instead, AibA/AibB seems to induce an intramolecular decarboxylation by binding its substrate in a hydrophobic cavity and forcing it into a bent conformation. Our study opens opportunities for synthetic biology studies, since AibA/AibB may be suitable for the production of isobutene, a precursor of biofuels and chemicals.     

An approach to characterization of the agricultural self-propelled machines stability

This paper presents an analytical algorithm with appropriate software specified for the approximation of the allowed critical slope of the solid flat terrain that guarantees static and/or dynamic stability of the specified self-propelled agricultural machines and their aggregates. This algorithm assumes machine as a rigid body, having 3 or 4 contact points (defined by wheels or crawlers), under uniform motion at different constant velocities and radii of curvature trajectories. Using this algorithm, based on the principles of theoretical mechanics combined with 3D analytical geometry, the computer program SSPM (stability of the self-propelled agricultural machines) has been coded. This software is intended to facilitate the analysis, comparison and optimization of different configurations of self-propelled agricultural machines in operation on horizontal and sloped flat terrains at constant velocities and radii of trajectory with respect to their static and dynamic stability. It calculates critical pitch and roll angles of the self-propelled machine and the maximum allowed slope of the flat terrain under the given conditions. The algorithm and the appropriate SSPM software were experimentally verified using the platform and low-scale tractor model. Average difference between calculated and experimental critical values of roll and pitch angles were about 4°     

The social responsibility of environmental analysis

A literature updated has been made on the academical studies focused on the social impact of environmental studies, paying attention to both, the quality of the information provided and the side effects of the methodology employed, also considering the importance of the analytical methodologies in the development of remediation processes and the key subject of the transmission of the environmental information to the policy makers and the general society.