PAMAM-calix-dendrimers: Synthesis and Thiacalixarene Conformation Effect on DNA Binding

A convenient method for the synthesis of the first generation PAMAM dendrimers based on the thiacalix[4]arene has been developed for the first time. Three new PAMAM-calix-dendrimers with the macrocyclic core in cone, partial cone, and 1,3-alternate conformations were obtained with high yields. The interaction of the obtained compounds with salmon sperm DNA resulted in the formation of the associates of the size up to 200 nm, as shown by the UV-Vis spectroscopy, DLS, and TEM. It was demonstrated by the CD method that the structure of the DNA did not undergo significant changes upon binding. The PAMAM-calix-dendrimer based on the macrocycle in cone conformation stabilized DNA and prevented its degradation.

Catechol-Containing Schiff Bases on Thiacalixarene: Synthesis, Copper (II) Recognition, and Formation of Organic-Inorganic Copper-Based Materials

For the first time, a series of catechol-containing Schiff bases, tetrasubstituted at the lower rim thiacalix[4]arene derivatives in three stereoisomeric forms, cone, partial cone, and 1,3-alternate, were synthesized. The structure of the obtained compounds was proved by modern physical methods, such as NMR, IR spectroscopy, and HRMS. Selective recognition (Kb difference by three orders of magnitude) of copper (II) cation in the series of d-metal cations (Cu2+, Ni2+, Co2+, Zn2+) was shown by UV-vis spectroscopy. Copper (II) ions are coordinated at the nitrogen atom of the imine group and the nearest oxygen atom of the catechol fragment in the thiacalixarene derivatives. High thermal stable organic-inorganic copper-based materials were obtained on the base of 1,3-alternate + Cu (II) complexes.

Biochemical reconstitutions reveal principles of human γ-TuRC assembly and function

The formation of cellular microtubule networks is regulated by the γ-tubulin ring complex (γ-TuRC). This ∼2.3 MD assembly of >31 proteins includes γ-tubulin and GCP2-6, as well as MZT1 and an actin-like protein in a “lumenal bridge” (LB). The challenge of reconstituting the γ-TuRC has limited dissections of its assembly and function. Here, we report a biochemical reconstitution of the human γ-TuRC (γ-TuRC-GFP) as a ∼35 S complex that nucleates microtubules in vitro. In addition, we generate a subcomplex, γ-TuRCΔLB-GFP, which lacks MZT1 and actin. We show that γ-TuRCΔLB-GFP nucleates microtubules in a guanine nucleotide–dependent manner and with similar efficiency as the holocomplex. Electron microscopy reveals that γ-TuRC-GFP resembles the native γ-TuRC architecture, while γ-TuRCΔLB-GFP adopts a partial cone shape presenting only 8–10 γ-tubulin subunits and lacks a well-ordered lumenal bridge. Our results show that the γ-TuRC can be reconstituted using a limited set of proteins and suggest that the LB facilitates the self-assembly of regulatory interfaces around a microtubule-nucleating “core” in the holocomplex.

Modifying a Partial Corn-sql Layer-based (3,3,3,3,4,4)-c Topological MOF by Substitution of OH- with Cl- and its Highly Selective Adsorption of C2 Hydrocarbons over CH4

Modifying VNU-18 (a MOF with the partial cone-sql layer pillared by the chains of pillars decorated with OH-) by substitution of OH- with Cl-, a new isoreticular structure, [Cu6(L)5•(Cl-)2•H2O•4DMF]•4DMF•6(H2O) (SNNU-Bai67,...

Biochemical reconstitutions reveal principles of human γ-TuRC assembly and function

The formation of cellular microtubule networks is regulated by the γ-tubulin ring complex (γ-TuRC). This ∼2.3 MDa assembly of >31 proteins includes γ-tubulin and GCP2-6, as well as MZT1 and an actin-like protein in a “lumenal bridge”. The challenge of reconstituting the γ-TuRC has limited dissections of its assembly and function. Here, we report a complete biochemical reconstitution of the human γ-TuRC (γ-TuRC-GFP), a ∼35S complex that nucleates microtubules in vitro. We extend our approach to generate a stable subcomplex, γ-TuRCmini-GFP, which lacks MZT1 and actin. Using mutagenesis, we show that γ-TuRCmini-GFP nucleates microtubules in a guanine nucleotide-dependent manner and proceeds with similar kinetics as reported for native γ-TuRCs. Electron microscopy reveals that γ-TuRC-GFP resembles the native γ-TuRC architecture, while γ-TuRCmini-GFP adopts a partial cone shape presenting only 8-10 γ-tubulin subunits and lacks a well-ordered lumenal bridge. Our structure-function analysis suggests that the lumenal bridge facilitates the self-assembly of regulatory interfaces around a microtubule-nucleating “core” in the γ-TuRC.

Mapping Out the Diversity of Lanthanide(III) Coordination Complexes Involving p-Sulfonatocalix[4,6]arenes

Structurally authenticated complexes of the cone-shaped p-sulfonatocalix[4]arene and conformationally flexible p-sulfonatocalix[6]arene devoid of co-ligands/ancillary molecules are limited. Early and late members of the lanthanide series as their trivalent ions, La3+, Er3+, and Yb3+, form complexes from aqueous media under these conditions. For La3+ and Er3+, distinct hydrophobic and hydrophilic bilayers are formed with p-sulfonatocalix[4]arene, whereas for Yb3+, two complexes form that deviate from the well-known bilayer arrangement of calixarenes. Replacing the calixarene with p-sulfonatocalix[6]arene results in a hydrogen-bonded network with alternating hydrophobic–hydrophilic layers associated with primary coordination of Yb3+, with the larger macrocyclic calixarene in a partial cone conformation.

The Pb-cone metric spaces over Banach algebra with applications

The aim of the article is to establish the structure of partial cone b-metric spaces over Banach algebras. Topological and structural properties are investigated of the new spaces. We also define generalized Lipschitz mappings and give their application in fixed point theory. The results presented in this paper substantially extend and strengthen the results of the literature. Few examples are provided to support our conclusions and as an application we establish the existence and uniqueness of a solution to a class of system of nonlinear integral equations.