pH-sensitive gels: By using a cyclohexane-based scaffold to which various amino acid based substituents can be connected, low-molecular-weight compounds were obtained that can gelate water at very low concentrations. Their modular design (see picture: AA = amino acid(s), X = hydrophilic substituent, dark purple = hydrophobic region, light purple = hydrophilic region), allows tuning of the thermally and pH-induced reversible gel-to-sol transition of their gels.
We present a simple analytical formalism based on the Lorentz-Scherrer equation and Bernoulli statistics for estimating the fraction of crystallites (and the associated uncertainty parameters) contributing to all finite Bragg peaks of a typical powder pattern obtained from a static polycrystalline sample. We test and validate this formalism using numerical simulations, and show that they can be applied to experiments using monochromatic or polychromatic (pink-beam) radiation. Our results show that enhancing the sampling efficiency of a given powder diffraction experiment for such samples requires optimizing the sum of the multiplicities of reflections included in the pattern along with the wavelength used in acquiring the pattern. Utilizing these equations in planning powder diffraction experiments for sampling efficiency is also discussed.
Protein kinases function as pivotal regulators in biological events, governing essential cellular processes through the transfer of phosphate groups from ATP molecules to substrates. Dysregulation of kinase activity is frequently associated with cancer, ocasionally arising from chromosomal translocation events that relocate genes encoding kinases. Fusion proteins resulting from such events, particularly those involving the proto-oncogene tyrosine-protein kinase ROS (ROS1), manifest as constitutively active kinases, emphasizing their role in oncogenesis. Notably, the chromosomal reallocation of the ros1 gene leads to fusion of proteins with the ROS1 kinase domain, implicated in various cancer types. Despite their prevalence, targeted inhibition of these fusion proteins relies on repurposed kinase inhibitors. This review comprehensively surveys experimentally determined ROS1 structures, emphasizing the pivotal role of X-ray crystallography in providing high-quality insights. We delve into the intricate interactions between ROS1 and kinase inhibitors, shedding light on the structural basis for inhibition. Additionally, we explore point mutations identified in patients, employing molecular modeling to elucidate their structural impact on the ROS1 kinase domain. By integrating structural insights with in vitro and in silico data, this review advances our understanding of ROS1 kinase in cancer, offering potential avenues for targeted therapeutic strategies.
Structural Biology plays a crucial role in understanding the Chemistry of Life by providing detailed information about the three-dimensional structures of biological macromolecules such as proteins, DNA, RNA and complexes thereof. This knowledge allows researchers to understand how these molecules function and interact with each other, which forms the basis for a molecular understanding of disease and the development of targeted therapies. For decades, X-ray crystallography has been the dominant technique to determine these 3D structures. Only a decade ago, advances in technology and data processing resulted in a dramatic improvement of the resolution at which structures of biomolecular assemblies can be determined using another technique: cryo-electron microscopy (cryo-EM). This has been referred to as “the resolution revolution”. Since then, an ever increasing group of structural biologists are using cryo-EM. They employ a technique named Single Particle Analysis (SPA), in which thousands of individual macromolecules are imaged. These images are then computationally iteratively aligned and averaged to generate a three-dimensional reconstruction of the macromolecule. SPA works best if a very pure and concentrated macromolecule of interest can be captured in random orientations within a thin layer (10-50nm) of vitreous ice. Maastricht University has been the inventor of the machine that is found in most labs worldwide used for this: the VitroBot. We have been the inventor of succeeding technologies that allow for much better control of this process: the VitroJet. In here, we will develop a novel chemical way to expand our arsenal for preparing SPA samples of defined thickness. We will design, produce and test chemical spacers to allow for a controlled sample thickness. If successful, this will provide an easy, affordable solution for the ~1000 laboratories worldwide using SPA, and help them with their in vitro studies necessary for an improved molecular understanding of the Chemistry of Life.
