Q-BioLiP:A Comprehensive Resource for Quaternary Structure-based Protein-ligand Interactions

Since its establishment in 2013,BioLiP has become one of the widely used resources for protein-ligand interactions.Nevertheless,several known issues occurred with it over the past decade.For example,the protein-ligand interactions are represented in the form of single chain-based tertiary structures,which may be inappropriate as many interactions involve multiple protein chains(known as quaternary structures).We sought to address these issues,resulting in Q-BioLiP,a comprehensive resource for quaternary structure-based protein-ligand interactions.The major features of Q-BioLiP include:(1)representing protein structures in the form of quaternary structures rather than single chain-based tertiary structures;(2)pairing DNA/RNA chains properly rather than separation;(3)providing both experimental and predicted binding affinities;(4)retaining both biologically relevant and irrelevant interactions to alleviate the wrong justification of ligands’biological relevance;and(5)developing a new quaternary structure-based algorithm for the modelling of protein-ligand complex structure.With these new features,Q-BioLiP is expected to be a valuable resource for studying biomolecule interactions,including protein-small molecule interaction,protein-metal ion interaction,protein-peptide interaction,protein-protein interaction,protein-DNA/RNA interaction,and RNA-small molecule interaction.Q-BioLiP is freely available at https://yanglab.qd.sdu.edu.cn/Q-BioLiP/.

Synthesis, Crystal Structure, Two-photon Absorption and Biological Imaging Application of a Water Soluble Carbazole Quaternary Ammonium Compound

A novel carbazole quaternary ammonium compound（abbreviated as T_2） had been synthesized and characterized by ~1H NMR, ^（13）C NMR and Mass spectrometry. The single-crystal structure has been determined by X-ray single-crystal diffraction. The electrochemical and two-photon absorption properties of T_2 were systematically studied by cyclic voltammetry and Z-scan determination methods, respectively. The results suggested that T_2 had a good oxidation-reduction and excellent nonlinear optical property. The two-photon absorption（TPA） value has a maximum corresponding to cross section σ = 7963.3 GM（Goeppert-Mayer units） at 700 nm, indicating potential applications in nonlinear optical materials. Furthermore, attributing to the excellent water solubility and low cytotoxicity, the compound was explored on its primary application in biological imaging.

Solvothermal Synthesis and Characterization of [TM(1,2-dap)3]HgSb2Se5(TM = Co,Fe)with a Chain Structure

One organic-decorated quanternaery [TM（1,2-dap）3]Hg Sb2Se5（1,2-dap = 1,2-dianinopropane, TM = Co（1）, Fe（2）） compound has been solvothermally synthesized. The compounds crystallize in triclinic space group P 1, with a = 11.248（6）, b = 11.542（7）, c = 12.180（12） A, V =1268.7（16） A^3, Z = 2, F（000） = 1010 for 1 and a = 11.311（5）, b = 11.558（5）, c = 12.180（9） A, V =1276.5（12） A^3, Z = 2, F（000） = 1008 for 2. The crystal structure consists of one-dimensional anionics chains composed of Hg Se4 tetrahedra and SbSe3 trigonal pyramids sharing corners and[TM（dap）3]^2＋ cations. The [HgSb2Se＋5^2-]∞ anionic chains run along the [001] direction, and are surrounded by the [TM（dap）3]^2＋ cations. Meanwhile, 8-ring [Hg2Sb2Se4] and 6-ring [HgSb2Se2] are alternately found. The compounds were structurally characterized by elemental analysis,thermogravimetric analysis, infrared spectroscopy and UV-Vis diffuse reflectance spectroscopy.