Israel Journal of Chemistry最新文献

The atomic-scale disorder of aperiodic crystals, and quasicrystals in particular, is inherently difficult to explore by experimental methods due to their complex atomic arrangements. Two advanced characterization techniques, a revived and an emerging one, offer direct experimental access even to such complex atomic structures: Diffuse Scattering and Atomic Resolution Holography. In this overview, we introduce their specific application to aperiodic crystals and discuss their merits and difficulties.

The cover art depicts the RNA catalyst ‘flexizyme’ based on its three-dimensional structure. It attaches a yellow sphere representing a non-canonical amino acid onto a tRNA, which is shown as a classical two-dimensional ‘cloverleaf’ representation. The catalyst is aided by two structural magnesium ions represented by small, darker red circles. Surrounding the flexizyme is a pool of acylated tRNA molecules and numerous macrocyclic peptides incorporating the non-canonical amino acids shown as colored circles.

Exploring nonminimal-rank quasicrystals, which have symmetries that can be found in both periodic and aperiodic crystals, often provides new insight into the physical nature of aperiodic long-range order in models that are easier to treat. Motivated by the prevalence of experimental systems exhibiting aperiodic long-range order with hexagonal and trigonal symmetry, we introduce a generic two-parameter family of 2-dimensional quasiperiodic tilings with such symmetries. We focus on the special case of trigonal and hexagonal Fibonacci, or golden-mean, tilings, analogous to the well studied square Fibonacci tiling. We first generate the tilings using a generalized version of de Bruijn's dual grid method. We then discuss their interpretation in terms of projections of a hypercubic lattice from six dimensional superspace. We conclude by concentrating on two of the hexagonal members of the family, and examining a few of their properties more closely, while providing a set of substitution rules for their generation.

Genetic code expansion aims to incorporate non-canonical amino acids (ncAAs) into biological systems, enhancing protein functionality or enabling the in vitro selection of peptides from diverse mRNA displayed libraries. Typically, genetic code expansion has involved reassignment of stop codons to ncAAs through orthogonal translation systems. This review instead focuses on efforts to expand the genetic code by breaking the redundancy of sense codons in vitro and in vivo. In vivo, orthogonal aminoacyl-tRNA synthetase (AARS)/tRNA/AA systems are able to compete with endogenous machinery, enabling partial to full codon reassignment. Recent approaches, like genome recoding, offer potential solutions to reduce competition. In vitro studies utilize cell extract-based or reconstituted translation systems, allowing precise control of codon usage via gene design and tRNA addition, making breaking of sense degeneracy easier. In these systems several unsplit codon boxes have been successfully reassigned multiple to ncAAs. These efforts showcase both the successes and challenges in achieving orthogonality and selective codon decoding and point towards a future where the 64 codons can encode more than 30 monomers, enabling new advances in synthetic biology and drug discovery.

The cover image shows amphiphilic calixarenes embedded in a phospholipid bilayer membrane. Anionic calixarenes facilitate counterion-mediated transport of positively charged peptides across said membranes highlighting the utility of amphiphilic calixarenes for peptide transport into liposome and for direct cytosolic delivery of charged molecules into cells, which still is a significant problem in the fields of biology and medicine. [the image refers to the article “Anionic Calixarenes in Biomembrane Transport of Peptides” by Justin Neumann and Andreas Hennig.]

Chemical Biology of Nucleic Acid Modifications II Issue editor: Chun-Xiao Song, Guifang Jia, Seraphine Wegner, and Chengqi Yi. The cover picture highlights Chuan He's wide-ranging research contributions across chemical biology, nucleic acid chemistry, biology, and epigenetics. His work focused on understanding DNA and RNA modifications in gene regulation. His groundbreaking discovery of reversible RNA modification revealed a new mode of gene regulation by RNA alongside DNA — and protein-based epigenetic mechanisms, leading to the emergence of the epitranscriptomics field.

The lifestyle of mankind has improved significantly since the start of the industrial revolution and the establishment of a science (engineering)-based society, some 250 years ago. Notwithstanding, the outcome of these advances, a major threat is looming on the future of humanity due to the greenhouse effect produced by fossil fuel effluents and the degradation of the environment on earth. Chemistry and chemical engineering are key players in confronting these challenges and establishing sustainable lifestyle on earth. In particular, the interplay between materials research; solid-state chemistry and nanoscience (nanotechnology) will be crucial for the future of sustainable life on earth. Education of the population-at-large to shift from a consumer-based society into sustainability-concerned lifestyle, is mandatory for realization of this paradigm shift. Harmonizing the interplay between entrepreneurs, financing bodies, public agencies, international organizations, legal bodies and research institutes should also play an integral part of this new equation.