Chemical approaches to the study of nucleoprotein structures

The main chemical approaches to the study of macromolecular structure and dynamics and to the elucidation of interbiopolymer contact points are considered and illustrated by particular examples. Primary attention is paid to the chemical footprinting and affinity modification methods. The use of bifunctional reagents for the study of nucleoprotein structure architecture is described. The ways of enhancing the selectivity of affinity modification available from the literature are analyzed with an emphasis on catalytically competent (superselective) labeling. The identification of proteins responsible for replication of the tickborne encephalitis virus by this method is described to demonstrate the possibility of the application of the method to multicomponent systems such as the nucleus fraction of infected cells. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1225–1231, July, 1999.     

Fast and Cysteine-Specific Modification of Peptides,Proteins and Bacteriophage Using Chlorooximes

This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k₂=306±4 M⁻¹s⁻¹ for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries.     

蚕丝改性方法概述

天然的蚕丝具有独特的优良性能,但同时也存在性能缺陷,如力学性能（拉伸强度与韧性）差,使用时间短以及色牢度差等。科学家们发展了蚕丝的改性技术,改良蚕丝的性能以达到更好的应用目的。目前常用的蚕丝改性方法主要分为基因改性方法、物理改性法、化学改性法及添食育蚕法等。概述了蚕丝的结构与改性的原理,介绍了4类改性法及其近年来取得的重要进展,总结了目前蚕丝改性研究中的难点,展望了蚕丝改性研究的未来发展方向。     

Highly efficient modification of DNA polymerase β under conditions of direct and sensitized activation of photoreactive DNAs. Modification of cell extract proteins

dUTP and dCTP derivatives containing a 4-azido-2,3,5,6-tetrafluorobenzylideneaminooxy group were incorporated into the 3′-end of the DNA primer within complexes with the DNA-matrix as analogs of natural dTTP by virtue of catalytic activity of DNA polymerase β or endogenous DNA polymerases of the cell extract. The photoreactive DNAs synthesized in situ were used for affinity modification of DNA polymerase β and DNA-binding proteins of the cell extract. For the photoreactive DNA based on these analogs, the efficiency of formation of covalent adducts with DNA polymerase β under the highest degree of DNA complexation with the enzyme was determined. The yield of covalent DNA adducts with the enzyme was 28–47%, depending on the type of the analog. The effect of the sequence of the DNA template near the localization of the photoreactive group on the redistribution of covalent cross-links between the possible targets was demonstrated. A possibility of increasing the efficiency of DNA polymerase β modification in the presence of a substantial excess of photoreactive DNA using a sensitizer, a dUTP derivative containing a pyrene residue, was studied. When photoreactive DNA containing a 2,3,5,6-tetrafluoro-4-azidobenzoyl (FAB) group was used, about 60% of DNA polymerase β was covalently attached to DNA. Photoreactive dNTP analogs ensuring a high level of protein modification in the cell extract were found. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1273–1283, May, 2005.     

层状复合氢氧化物的有机改性方法及应用研究进展

层状复合氢氧化物(LDHs)因其化学组成可调、比表面积大、生物相容性好等特点,目前在环境、能源和生物医药等领域广受关注.然而, LDHs在合成过程中由于其分子内作用力易发生团聚而导致其在基体中的分散不均匀,极大地限制了LDHs在实际中的应用.有机改性是改善LDHs分散性的有效方法,从表面改性和插层改性两个方面综述了近年来LDHs的有机改性方法,并介绍了其在阻燃、吸附、催化、气体阻隔、发光、储能和生物医药材料等领域的应用.最后对改性后LDHs未来的研究方向和应用领域进行了展望.     

热塑性淀粉耐水性的化学与物理作用机制

石油资源的短缺以及减轻石油基聚合物所产生的环境负担的必要性,推动了生物可降解材料的开发和生产。近几十年来天然聚合物由于无毒性、可生物降解性和生物相容性正在某些领域取代目前的合成聚合物。淀粉由于其可再生性、可生物降解性、低成本和易获得性已经被广泛研究用于制造可生物降解的复合材料,应用于农业、食品、医药和包装行业。但淀粉的多羟基结构赋予其很强的亲水性,这种湿度敏感性限制了它们的机械性能并影响到其应用。本文主要从提高热塑性淀粉耐水性的物理与化学作用机理的角度出发,总结和归纳了近年来国内外以提高热塑性淀粉材料的耐水性能和降低其对环境湿度敏感性为目的的研究工作,介绍了影响耐水性能的相关因素以及改善方法,并指出今后研究工作的发展方向。     

Reinforced Modification of PEEK and its Applications

聚醚醚酮（PEEK）作为一种特种热塑性工程塑料,在许多工程领域有着广泛的应用。采用不同手段改性聚醚醚酮,改善其热学性能、力学性能、摩擦学性能和加工性能等,有利于降低生产成本和进一步拓展其应用范围。本文从化学改性和纤维增强、无机填充、表面改性、与有机共混等物理改性两个方面综述了近年来国内外聚醚醚酮改性研究进展情况,以及对其在工业领域、电子电器领域、航空领域、汽车领域和医学领域中的应用作了简单的概括,最后展望了聚醚醚酮改性研究开发问题及解决方法。     

淀粉基高分子材料的研究进展

概述了近5年国内外在淀粉的化学、物理改性及其作为一种材料使用方面取得的最新研究进展.淀粉的化学改性主要介绍了淀粉的酯化、醚化、氧化、交联、接枝共聚等,而物理改性主要介绍了淀粉分别与黏土、脂肪族聚酯、聚乙烯醇以及纤维素等天然大分子的共混改性,同时还介绍了通过酸化制备淀粉纳米晶.淀粉基材料除了用于制备可生物降解塑料、吸附材...     

淀粉衍生物的研究及应用

简要介绍了淀粉的结构和特点,以及物理改性、化学改性和酶法改性的基本原理,着重介绍了化学改性的基本原理,详细介绍了氧化淀粉、醚化淀粉和酯化淀粉的制备及应用,并对淀粉衍生物的研究方向作了展望,认为复合改性淀粉是未来淀粉化学品的发展趋势。淀粉衍生物可广泛应用于食品、纺织、造纸、医药等众多领域,具有广阔的发展前景。     

Functional Polymers. XXII. Ultraviolet Absorbers with 2(2-Hydroxyphenyl)2H-benzotriazole and 2-Hydroxybenzophenone (or Acetophenone) Chromophors in the Same Molecule

Benzotriazolization of 2,4-dihydroxyacetophenone and 2,4-dihydroxybenzophenone has given dibenzotriazolized products: 3,5- [di (2H-benzotriazole-2-yl)]2,4-dihydroxyacetophenone, and 3,5-[di (2H-benzotriazole-2-yl)] 2,4-dihydroxybenzophenone. These compounds are expected to be effective and useful UV absorbers as they both have the 2 (2-hydroxyphenyl)2H-benzotriazole unit and the 2-hydroxybenzophenone (or acetophenone) unit in the molecule. The compounds were characterized by their spectral behavior and particularly by careful study of their UV spectrum.     

改性高分子超滤膜的研究进展

随着超滤膜技术的发展,人们对膜材料的性能不断提出新的要求,其中改善膜的亲水性,提高膜的抗污染能力已成为有待解决的迫切问题.由于单一的膜材料很难同时具有良好的亲水性、成膜性、热稳定性、化学稳定性、耐酸碱性、耐微生物性侵蚀、耐氧化性和较好的机械强度等优点,因此采用膜材料改性或膜表面改性的方法来提高膜的性能,是解决这一问题的关键.本文介绍了目前国内外高分子超滤膜材料改性中常用的化学改性和物理改性方法.其中,化学改性可以通过膜材料和膜表面的化学改性来实现;而物理改性则主要是通过材料改性来实现.     

改性低分子量聚异戊二烯橡胶的合成与应用

采用阴离子溶液聚合法合成了低分子量3,4-聚异戊二烯(LPI), 并对其进行改性, 制备了硅氧烷改性的低分子量3,4-聚异戊二烯(MLPI), 将其应用于白炭黑补强的溶聚丁苯橡胶(SSBR)复合材料, 探究了端基改性物LPI-丙基甲基二甲氧基硅烷(LPI-CMDS)、 LPI-丙基三甲氧基硅烷(LPI-CTMS)、 LPI-丙基三乙氧基硅烷(LPI-CTES)和接枝改性物3-巯丙基三乙氧基硅烷接枝改性LPI(LPI-g-MTS)对SSBR复合材料中白炭黑的分散以及硫化胶性能的影响. 混炼胶的应变扫描和结合胶含量分析结果表明, MLPI增强了填料与聚合物之间的相互作用, 改善了白炭黑在复合材料中的分散, 其中LPI-g-MTS因活性位点多, 效果最佳; 与填充LPI的复合材料相比, 硫化胶的物理机械性能, 尤其是填充LPI-g-MTS后硫化胶的300%定伸应力和拉伸强度分别提升了89.66%和27.15%, 这为改善白炭黑在非极性橡胶中的分散提供了一条新途径.     

Investigation into the surface modification of aragonite whiskers

Aragonite whiskers (AWs) were treated with several fatty acid surfactants and silane coupling agent in order to determine the optimal modifier by using contact angle measurements. The results revealed that the AWs modified by fatty acids showed more remarkable increase in the contact angle than by silane, suggesting the former were preferentially applied in modifying AWs. While the samples coated with fatty acids exhibited hydrophobicity with contact angles ranging from 104.08° to 137.87° with increasing of carbon chain length. Therefore, the highest contact angle of AWs treated by oleic acid was discussed in detail as an example, which was characterized by field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), thermo‐gravimetry analyses (TGA), X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). FESEM and TEM results showed a thin layer coated on the modified sample surface. Both the results of TGA and XPS confirmed organic groups existed in the sample of AWs treated by oleic acid. FTIR demonstrated that calcium dioleate was formed in the modification process. Further, modification mechanism was proposed based on the obtained results. Copyright © 2016 John Wiley & Sons, Ltd.     

Recent Progress and Perspectives on Cell Surface Modification

The cell membrane is a biological interface consisting of phospholipid bilayer, saccharides and proteins that maintains a stable metabolic intracellular environment as well as regulating and controlling the exchange of substances inside and outside the cell. Cell membranes provide a highly complex biological surface carrying a variety of essential surfaces ligands and receptors for cells to receive various stimuli of external signals, thereby inducing corresponding cell responses regulating the life activities of the cell. These surface receptors can be manipulated via cell surface modification to regulate cellular functions and behaviors Thus, cell surface modification has attracted considerable attention due to its significance in cell fate control, cell engineering and cell therapy. In this minireview, we describe the recent developments and advances of cell surface modification, and summarize the main modification methods with corresponding functions and applications. Finally, the prospect for the future development of the modification of the living cell membrane is discussed.     

Deciphering nucleic acid modifications by chemical derivatization-mass spectrometry analysis

Chemical derivatization in combination with mass spectrometry (MS) analysis is a promising strategy for the sensitive and effective analysis of nucleic acid modifications. In this review, we summarize the recent advances for deciphering modifications in DNA and RNA by chemical derivatization-MS analysis.     

A General Approach Towards Triazole‐Linked Adenosine Diphosphate Ribosylated Peptides and Proteins

Current methods to prepare adenosine diphosphate ribosylated (ADPr) peptides are not generally applicable due to the labile nature of this post‐translational modification and its incompatibility with strong acidic conditions used in standard solid‐phase peptide synthesis. A general strategy is presented to prepare ADPr peptide analogues based on a copper‐catalyzed click reaction between an azide‐modified peptide and an alkyne‐modified ADPr counterpart. The scope of this approach was expanded to proteins by preparing two ubiquitin ADPr analogues carrying the biological relevant α‐glycosidic linkage. Biochemical validation using Legionella effector enzyme SdeA shows that clicked ubiquitin ADPr is well‐tolerated and highlights the potential of this strategy to prepare ADPr proteins.     

废旧塑料改性再生的研究进展

塑料制品作为一种全球范围内广泛使用的商品,几乎已经渗透到了人类生活中的各个方面。同时,快速累积的废旧塑料对陆地和海洋环境产生了一系列的负面影响。值得注意的是,废旧塑料具有资源和废物双重属性。废旧塑料的回收品质和数量的提高,对于资源的高效利用、可持续发展和环境保护具有重大意义。本文介绍了废旧塑料常用的分选方法,综述了近年来国内外废旧塑料化学改性和物理改性的研究进展,并分析了废旧塑料改性再生所面临的问题。     

Surface modification of polystyrene by blending substituted styrene copolymers

The surface modification of polystyrene (PS) by the blending of 4‐acetoxystyrene polymers and their corresponding hydrolysis products, 4‐hydroxystyrene polymers, was investigated on the basis of X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact‐angle measurements. According to XPS and AFM measurements, when polystyrene‐block‐poly(4‐acetoxystyrene) (PS‐b‐PAS) or polystyrene‐block‐poly(4‐hydroxystyrene) (PS‐b‐PHS) was incorporated into PS, the block copolymer was preferentially segregated at the highest surface region of the blend. This segregation increased to a plateau value when more than 5 wt % of either PS‐b‐PHS or PS‐b‐PAS was added. The contact angle of the modified PS by PS‐b‐PAS or PS‐b‐PHS was slightly lower than that of homopolystyrene, but no further decrease was observed with the blend ratio of the diblock copolymer increasing from 5 to 20 wt %. For a PS/PS‐b‐PHS blend, the surface atomic concentration ratio O/C increased linearly with the molecular weight of poly(4‐hydroxystyrene) blocks in diblock copolymer PS‐b‐PHS in the range of our study. The different structures of 4‐acetoxystyrene polymers and their hydrazinolyzed materials may affect the surface compositions of their blends with PS; among these polymers, PS‐b‐PHS and PS‐b‐PAS appeared to be most effective. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1046–1054, 2001     

Modification of mono-dispersed silica colloid particles with polymer silane coupling agents

The reaction of monodispersed silica colloid with hydrophobic and hydrophilic polymer coupling agents in the presence of ammonia afforded dispersible polymer/SiO₂ composites into organic solvents without aggregation.     

Highly hydrophobic sisal chemithermomechanical pulp (CTMP) paper by fluorotrimethylsilane plasma treatment

Fluorinated thin layers were created on chemithermomechanical pulp (CTMP) sisal paper surfaces with fluorotrimethylsilane (FTMS) radio frequency-plasma conditions. It was found that the FTMS-discharge environments caused implantation of fluorine and –Si(CH₃) _x groups into the surface layers of the paper substrates. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and Electron Spectroscopy for Chemical Analysis, as well as Atomic Force Microscopy and Scanning Electron Microscopy analyses revealed a smooth surface for the FTMS plasma-treated paper, apparently covered completely with a cross-linked polymerized network. Although the plasma reaction takes place with the cellulose, hemicelluloses and lignin, it appears that the chemical linkage is mainly to the lignin component on the CTMP paper surface by means of mainly C–O–Si–F, with some C–Si–F structures. The CTMP fibers apparently have a high lignin surface concentration. The water absorption for the plasma-treated CTMP paper was reduced from greater than 300 to 17 g of water/m² and the contact angle increased from less than 15° to greater than 120° the strength properties were only slightly reduced and the brightness was essentially unaffected with the FTMS plasma treatment.