Genetic diversity analysis in the traditional and improved ginger (Zingiber officinale Rosc.) clones cultivated in North-East India

Cyclodipeptides (CDPs) or 2,5-diketopiperazines (DKPs) can exert a variety of biological activities and display pronounced resistance against enzymatic hydrolysis as well as a propensity towards self-assembly into gels, relative to the linear-dipeptide counterparts. They have attracted great interest in a variety of fields spanning from functional materials to drug discovery. This concise review will analyze the latest advancements in their synthesis, self-assembly into gels, and their more innovative applications.

Diketopiperazine Gels: New Horizons from the Self-Assembly of Cyclic Dipeptides

Modeling the Conformational Preference, Spectral Analysis and Other Quantum Mechanical Studies on Three Bioactive Aminobenzoate Derivatives and Their SERS Active Graphene Complexes

The benzothiazolium salt, Thioflavin T (ThT), has been widely adopted as the "gold-standard" fluorescent reporter of amyloid in vitro. Its properties as a molecular rotor result in a large-scale (∼1000-fold) fluorescence turn-on upon binding to β-sheets in amyloidogenic proteins. However, the complex photophysics of ThT combined with the intricate and varied nature of the amyloid binding motif means these interactions are poorly understood. To study this important class of fluorophores, we present a detailed photophysical characterization and comparison of a novel library of 12 ThT-inspired fluorescent probes for amyloid protein (PAPs), where both the charge and donor capacity of the heterocyclic and aminobenzene components have been interrogated, respectively. This enables direct photophysical juxtaposition of two structural groups: the neutral "PAP" (class 1) and the charged "mPAP" fluorophores (class 2). We quantify binding and optical properties at both the bulk and single-aggregate levels with some derivatives showing higher aggregate affinity and brightness than ThT. Finally, we demonstrate their abilities to perform super-resolution imaging of α-synuclein fibrils with localization precisions of ∼16 nm. The properties of the derivatives provide new insights into the relationship between chemical structure and function of benzothiazole probes.

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A Comparative Photophysical Study of Structural Modifications of Thioflavin T-Inspired Fluorophores

Here, we present the first example of sp3 hybridized carbon centered (Csp3) tetrel bonding mediated 3D BODIPY assembly via the exceptional synergy of Csp3⋯N and Csp3⋯F pair interactions. The carbon tetrel bond interaction energies of Csp3⋯N and Csp3⋯F are amplified significantly as the size of the 1D chain grows from dimer to tetramer BODIPY units.

Carbon (sp3) tetrel bonding mediated BODIPY supramolecular assembly via unprecedented synergy of Csp3⋯N and Csp3⋯F pair interactions

Cis-trans isomerization of amide bonds impedes de novo design of folded peptoids (poly-N-substituted glycines) with precise secondary structures and affects peptoid-biomolecule binding affinity. Herein, from X-ray, NMR and DFT studies of azapeptoids, we have discovered a tetrel bonding interaction that stabilizes trans-peptoids. We show that peptoids having α-heteroatoms and N-aryl groups in the sidechain adopt trans-amide geometries due to the presence of a nX/πAr → σ*Cα-N tetrel bonding interaction between the sidechain α-heteroatom lone pair (nX) or π-electrons (πAr) and the σ* orbital of the backbone Cα-N bond. Further, CD spectroscopic studies of oligo-proline host-guest model peptides showed that azapeptoid residues stabilize polyproline II helical conformation. These data indicate that the sidechain-backbone tetrel bonding could be leveraged to design peptoids with precise secondary structures for a wide range of biological and material applications.

Kalpita Baruah

Papers

Sidechain-Backbone Tetrel Bonding Interactions Provide a General Mechanism for trans-Peptoid Stabilization.