Self-Assembly of DNA–Peptide Supermolecules: Coiled-Coil Peptide Structures Templated by d-DNA and l-DNA Triplexes Exhibit Chirality-Independent but Orientation-Dependent Stabilizing Cooperativity

DNA nanostructures have been designed and used in many different applications. However, the use of nucleic acid scaffolds to promote the self-assembly of artificial protein mimics is only starting to emerge. Herein five coiled-coil peptide structures were templated by the hybridization of a d -DNA triplex or its mirror-image counterpart, an l -DNA triplex. The self-assembly of the desired trimeric structures in solution was confirmed by gel electrophoresis and small-angle X-ray scattering, and the stabilizing synergy between the two domains was found to be chirality-independent but orientation-dependent. This is the first example of using a nucleic acid scaffold of l -DNA to template the formation of artificial protein mimics. The results may advance the emerging POC-based nanotechnology field by adding two extra dimensions, that is, chirality and polarity, to provide innovative molecular tools for rational design and bottom-up construction of artificial protein mimics, programmable materials and responsive nanodevices.     

略论相似相溶原理的内涵与部分应用*

相似相溶原理在中学教学实践中的相关内涵与应用细节不够明确,使用较为笼统。总结了“相溶”和“相似”2个术语的部分内涵,解释了相似相溶原理在中学化学中的部分应用疑惑。     

4-Dimethylaminochalcone as a f luorescent probe: Quantum chemical calculations of its interaction with the environment

Ground-state RHF/6-311G(d,p) and density functional B3LYP/6-311G(d,p) quantum chemical calculations of 4-dimethylaminochalcone (DMAC), a sensitive fluorescent probe, were carried out for vacuum and for solvents of different polarity. The effect of the medium was included by the SCRF method in the framework of the polarization continuum model. The DMAC fragment comprising the aniline and propenone groups has a nearly planar conformation. The phenyl group can lie in the same plane or rotate by an angle within the limits of ±20° with a low barrier at 293 K. The results of calculations were confirmed by the data of X-ray study, according to which the phenyl group in the crystal is rotated by 20°. Calculations with allowance for solvation effects predict charge transfer from the dimethylamino group to the oxygen atom; the higher the medium polarity, the larger the degree of charge transfer (atomic charge of oxygen increases by 0.07 e in acetone). The calculated dipole moment of the DMAC molecule increases from 5.2 D (vacuum) to 5.9 D (heptane) and 6.9 D (acetone), which is in agreement with spectroscopic data. The energy of the DMAC—environment interaction was calculated. Due to large dipole moment of the DMAC molecule, the electrostatic component of this energy strongly depends on the environment polarity, which can be related to redistribution of the probe between the aqueous phase and cells and lipid structures of lipoproteins. The electronic absorption spectra of DMAC in solvents of different polarity were calculated; differences between the calculated and experimentally measured values are at most 15 nm. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1674–1679, October, 2006.     

A useful approximation scheme for Lagrangians

We present a new, useful approximation scheme for the integrand of an integral functional, revolving around a generalized bipolarity result. This scheme leads immediately to lower semicontinuity and lower closure results for the integral functional, as well as to other, more general seminormality properties.     

Unitals and Unitary Polarities in Symmetric Designs

We extend the notion of unital as well as unitary polarity from finite projective planes to arbitrary symmetric designs. The existence of unitals in several families of symmetric designs has been proved. It is shown that if a unital in a point-hyperplane design PG _d-1(d,q) exists, then d = 2 or 3; in particular, unitals and ovoids are equivalent in case d = 3. Moreover, unitals have been found in two designs having the same parameters as the PG ₄(5,2), although the latter does not have a unital. It had been not known whether or not a nonclassical design exists, which has a unitary polarity. Fortunately, we have discovered a unitary polarity in a symmetric 2-(45,12,3) design. To a certain extent this example seems to be exceptional for designs with these parameters.     

Synthesis and antibacterial evaluation of new sulfanyltetrazole derivatives bearing piperidine dithiocarbamate moiety

A series of new alkyl or aryl sulfanyltetrazole derivatives containing dithiocarbamate moiety (5a–6e) were synthesized. The structures of the compounds were characterized by IR, ¹H NMR, ¹³C NMR spectra, and elemental analysis data. The present study examines the antibacterial potential of novel synthetic sulfanyltetrazole compounds against clinically important gram-positive and -negative strains. The results of screening showed that attachment of dithiocarbamate to sulfanyltetrazole derivatives results in enhancement of antibacterial activity. The compound 6d showed the best activity among the tested compounds. Also, the less polar 2,5-disubstituted sulfanyltetrazole regioisomers showed an increased antibacterial activity compared with the corresponding more polar regioisomers.     

Influence of structure and polarity of polysiloxanes on retention of N-TFA butyl esters of amino acids

In this work, we have investigated the influence of the polarities and structures of 13 polysiloxanes on the retention of some N-TFA N-butyl esters of amino acids. Gehrke [1] was the first to examine the possible relationship between polarity and retention data of amino acid derivatives for 9 stationary liquid phases. He concluded that the molecular structure of the stationary liquid phase is an important factor determining retention.     

Structure of adsorption layers of ionic surfactants at the solid/liquid interface

A large number of experimental results of different surfactant adsorption systems (mainly on the silicas) obtained from both equilibrium and kinetic studies under different conditions are interpreted by a model of small individual surface aggregates. The adsorption model is contrasted with the influences of various factors, including electrostatic interaction, hydrophobic interaction, concentrations, types of coions, types of counterions, surfactant structure, alkyl chain length, types of head groups, neutral electrolytes, pH, adsorbent structure, porosity, surface charge density, and surface polarity.Dedicated to Frau Professor Dr. Elsa Ullmann on the occasion of her 80th birthday     

正规苯型烃的命名及对称性分类

正规苯型烃的命名及对称性分类贾金萍王爱坤（河北科技大学）何文辰（河北工业大学，天津３００１３０）关键词本型烃正规苯型烃苯型烃（稠环芳烃）是一系列苯环稠接而成的化合物，是介于苯与石墨间的多种有机化合物的统称。如能在氢气氛中将石墨裂解就有可能得到各种苯型...     

降冰片二烯衍生物光敏异构化反应的机理研究

利用甲基卡唑为光敏剂，实现了三个降冰片二烯衍生物的光诱导介键异构化反应，荧光猝灭，化学诱导动态核极化（ＣＩＤＮＰ）以及热力学讨论都支持电子转移敏化机理，有关量子效率的计算表明单重态电子转移机制对光异构化反应的贡献远大于三重态能传递机制，此外还探讨了光异构化反应中的溶剂极性效应。