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1. chinaXiv:201605.01802 [pdf]

Environmentally responsive polymeric materials: effect of the topological structure on self-assembly

Wang, Hui; Zhang, Pei; Shi, Xuefeng; Yu, Danfeng; Wang, Jinben; Yan, Haike; Ji, Gang
Subjects: Biology >> Biophysics

A novel amphiphilic homopolymer (PAGC(8)), containing two hydrophilic head groups and double hydrophobic tails in each repeat unit, has been prepared by solution polymerization and named as "a geminized amphiphilic homopolymer" in this paper, which is capable of self-assembling into various nanoobjects depending on the solution concentration and solvent properties. Characterization of the self-assembly behaviors was carried out by steady-state fluorescence, transmission electron microscopy and nuclear magnetic resonance techniques. Particular emphasis was dedicated to the environmental responsiveness of the assemblies. The morphologies were observed to transform from micelle-type to vesicles on adding a certain amount of ethanol. It is noteworthy that the assemblies were able to trap hydrophilic (rhodamine B) and hydrophobic (Sudan Red) molecules. Subsequently different nanoobjects were found after the encapsulation. To probe the effect of the topological structure on the self-assembly behaviors, the properties of an additional homopolymer with single charge pendant architecture on the backbone were investigated for comparison. Significant differences in structure between the two architectures brought out remarkable variations in aggregates, which were non-responsive to the solvent environment, or encapsulation of molecules. Based on the experimental results, we proposed a possible mechanism of the morphological transitions of the assemblies.

submitted time 2016-05-18 Hits2358Downloads801 Comment 0

2. chinaXiv:201605.01349 [pdf]

Insight into the three-dimensional structure of maize chlorotic mottle virus revealed by Cryo-EM single particle analysis

Wang, Chun-Yan; Zhou, Xue-Ping; Hong, Jian; Zhang, Chuan-Xi; Zhang, Qin-Fen; Gao, Yuan-Zhu; Ji, Gang; Huang, Xiao-Jun
Subjects: Biology >> Biophysics

Maize chlorotic mottle virus (MCMV) is the only member of the Machlomovirus genus in the family Tombusviridae. Here, we obtained the Cryo-EM structure of MCMV by single particle analysis with most local resolution at approximately 4 angstrom. The C alpha backbone was built based on residues with bulky side chains. The resolved C-terminus of the capsid protein subunit and obvious openings at the 2-fold axis demonstrated the compactness of the asymmetric unit, which indicates an important role in the stability of MCMV. The Asp116 residue from each subunit around the 5-fold and 3-fold axes contributed to the negative charges in the centers of the pentamers and hexamers, which might serve as a solid barrier against the leakage of genomic RNA. Finally, the loops most exposed on the surface were analyzed and are proposed to be potential functional sites related to MCMV transmission. (C) 2015 Elsevier Inc. All rights reserved.

submitted time 2016-05-11 Hits704Downloads367 Comment 0

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