Macromolecular assemblies such as protein complexes and protein/RNA condensates are involved in most fundamental cellular processes.The arrangement of subunits within these nano-assemblies is critical for their biolog...Macromolecular assemblies such as protein complexes and protein/RNA condensates are involved in most fundamental cellular processes.The arrangement of subunits within these nano-assemblies is critical for their biological function and is determined by the topology of physical contacts within and between the subunits forming the complex.Describing the spatial arrangement of these interactions is of central importance to understand their functional and stability consequences.In this concept article,we propose a circuit topology-based formalism to define the topology of a complex consisting of linear polymeric chains with interand intrachain interactions.We apply our method to a system of model polymer chains as well as protein assemblies.We show that circuit topology can categorize different forms of chain assemblies.Our multi-chain circuit topology should aid analysis and predictions of mechanistic and evolutionary principles in the design of macromolecular assemblies.展开更多
Five neutral macromolecular polyester gadolinium (Ⅲ) complexes with pendant hydrophobic alkyland aromatic functional groups were prepared. The longitudinal relaxation rates of these complexes weremeasured. One of the...Five neutral macromolecular polyester gadolinium (Ⅲ) complexes with pendant hydrophobic alkyland aromatic functional groups were prepared. The longitudinal relaxation rates of these complexes weremeasured. One of these Gd (Ⅲ) complexes was chosen for the acute toxicity test and T_1-weighted imagingmeasurement. Preliminary results showed that. compared with Gd-DTPA. the neutral macromoleculargadolinium (Ⅲ) complexes provide higher T_1 relaxivity enhancement and longer function duration.展开更多
The construction procedure and structure of Ni2 +macromolecular complexes with series of poly styrene and maleic anhydride(PSt/MA)were studied.Both the copolymers and the complexes(Ni-PSt/MA)were characterized by mean...The construction procedure and structure of Ni2 +macromolecular complexes with series of poly styrene and maleic anhydride(PSt/MA)were studied.Both the copolymers and the complexes(Ni-PSt/MA)were characterized by means of FTIR, elemental analysis,gel permeation chromatography(GPC)and atomic adsorption spectrometer(AAS).A further study using PSt/MA as chelating resin to recover Ni2 +was performed.The adsorption behavior for Ni 2+and various relating parameters of PSt/MA in the separation process were determined.The results indicate that the adsorption capability varies with pH values and the PSt/MA can recover Ni2 +in higher adsorption rate and higher selective coefficient from a mixed solution containing light metals such as Ca 2+and Mg2 +impurities.展开更多
Exactly how the immune system discriminates between all environmental antigens to which it reacts vs. all selfantigens to which it does not, is a principal unanswered question in immunology. As set forth in this revie...Exactly how the immune system discriminates between all environmental antigens to which it reacts vs. all selfantigens to which it does not, is a principal unanswered question in immunology. As set forth in this review, because of the advances in our understanding of the immune system that have occurred in the last 50 years, for the first time it is possible to formulate a new theory, termed the ＂Quantal Theory of Immunity＂, which reduces the problem from the immune system as a whole, to the individual cells comprising the system, and finally to a molecular explanation as to how the system behaves as it does.展开更多
A novel supramolecular graft copolymer （SGP） composed of viologen-containing copolymer （P（DMA-co- diEV）） as the main chain and Np ended PNIPAM （Np-PNIPAm） as the grafts is prepared （DMA： N,N- dimethylacryami...A novel supramolecular graft copolymer （SGP） composed of viologen-containing copolymer （P（DMA-co- diEV）） as the main chain and Np ended PNIPAM （Np-PNIPAm） as the grafts is prepared （DMA： N,N- dimethylacryamide, diEV： ethylviologen dimer, Np： naphthalene, PNIPAM： poly（N-isopropylacrylamide））. The grafting is based on the triple complexation among a host of cucurbit[8]uril （CB[8]） and two vips of diEV and Np, which is characterized by UV-vis spectra and ITC. Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle （NCCM） at high temperature. The micelles are sensitive to reducing agents, for example Na2S203, which breaks the current inclusion complex pair and induces aggregation.展开更多
BACKGROUND： The 26S proteasome is at the heart of the ubiquitin-proteasome system, which is the key cellular pathway for the regulated degradation of proteins and enforcement of protein quality control. The 26S prote...BACKGROUND： The 26S proteasome is at the heart of the ubiquitin-proteasome system, which is the key cellular pathway for the regulated degradation of proteins and enforcement of protein quality control. The 26S proteasome is an unusually large and complicated protease comprising a 28-subunit core particle （CP） capped by one or two 19-subunit regulatory particles （RP）. Multiple activities within the RP process incoming ubiquitinated substrates for eventual degradation by the barrel-shaped CE The large size and elaborate architecture of the proteasome have made it an exceptional model for understanding mechanistic themes in macromolecular assembly. OBJECTIVE： In the present work, we highlight the most recent mechanistic insights into proteasome assembly, with particular emphasis on intrinsic and extrinsic factors regulating proteasome biogenesis. We also describe new and exciting questions arising about how proteasome assembly is regulated and deregulated in normal and diseased cells. METHODS： A comprehensive literature search using the PubMed search engine was performed, and key findings yielding mechanistic insight into proteasome assembly were included in this review. RESULTS： Key recent studies have revealed that proteasome biogenesis is dependent upon intrinsic features of the subunits themselves as well as extrinsic factors, many of which function as dedicated chaperones. CONCLUSION： Cells rely on a diverse set of mechanistic strategies to ensure the rapid, efficient, and faithful assembly of proteasomes from their cognate subunits. Importantly, physiological as well as pathological changes to proteasome assembly are emerging as exciting paradigms to alter protein degradation in vivo.展开更多
文摘Macromolecular assemblies such as protein complexes and protein/RNA condensates are involved in most fundamental cellular processes.The arrangement of subunits within these nano-assemblies is critical for their biological function and is determined by the topology of physical contacts within and between the subunits forming the complex.Describing the spatial arrangement of these interactions is of central importance to understand their functional and stability consequences.In this concept article,we propose a circuit topology-based formalism to define the topology of a complex consisting of linear polymeric chains with interand intrachain interactions.We apply our method to a system of model polymer chains as well as protein assemblies.We show that circuit topology can categorize different forms of chain assemblies.Our multi-chain circuit topology should aid analysis and predictions of mechanistic and evolutionary principles in the design of macromolecular assemblies.
基金Project supported by the Chinese Academy of Sciences and the State Sciences and Technology Commission of China.
文摘Five neutral macromolecular polyester gadolinium (Ⅲ) complexes with pendant hydrophobic alkyland aromatic functional groups were prepared. The longitudinal relaxation rates of these complexes weremeasured. One of these Gd (Ⅲ) complexes was chosen for the acute toxicity test and T_1-weighted imagingmeasurement. Preliminary results showed that. compared with Gd-DTPA. the neutral macromoleculargadolinium (Ⅲ) complexes provide higher T_1 relaxivity enhancement and longer function duration.
文摘The construction procedure and structure of Ni2 +macromolecular complexes with series of poly styrene and maleic anhydride(PSt/MA)were studied.Both the copolymers and the complexes(Ni-PSt/MA)were characterized by means of FTIR, elemental analysis,gel permeation chromatography(GPC)and atomic adsorption spectrometer(AAS).A further study using PSt/MA as chelating resin to recover Ni2 +was performed.The adsorption behavior for Ni 2+and various relating parameters of PSt/MA in the separation process were determined.The results indicate that the adsorption capability varies with pH values and the PSt/MA can recover Ni2 +in higher adsorption rate and higher selective coefficient from a mixed solution containing light metals such as Ca 2+and Mg2 +impurities.
文摘Exactly how the immune system discriminates between all environmental antigens to which it reacts vs. all selfantigens to which it does not, is a principal unanswered question in immunology. As set forth in this review, because of the advances in our understanding of the immune system that have occurred in the last 50 years, for the first time it is possible to formulate a new theory, termed the ＂Quantal Theory of Immunity＂, which reduces the problem from the immune system as a whole, to the individual cells comprising the system, and finally to a molecular explanation as to how the system behaves as it does.
基金Ministry of Science and Technology of China(Nos. 2011CB932503 and 2009CB930402)National Natural Science Foundation of China(No.91227203) are acknowledged for their financial support
文摘A novel supramolecular graft copolymer （SGP） composed of viologen-containing copolymer （P（DMA-co- diEV）） as the main chain and Np ended PNIPAM （Np-PNIPAm） as the grafts is prepared （DMA： N,N- dimethylacryamide, diEV： ethylviologen dimer, Np： naphthalene, PNIPAM： poly（N-isopropylacrylamide））. The grafting is based on the triple complexation among a host of cucurbit[8]uril （CB[8]） and two vips of diEV and Np, which is characterized by UV-vis spectra and ITC. Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle （NCCM） at high temperature. The micelles are sensitive to reducing agents, for example Na2S203, which breaks the current inclusion complex pair and induces aggregation.
文摘BACKGROUND： The 26S proteasome is at the heart of the ubiquitin-proteasome system, which is the key cellular pathway for the regulated degradation of proteins and enforcement of protein quality control. The 26S proteasome is an unusually large and complicated protease comprising a 28-subunit core particle （CP） capped by one or two 19-subunit regulatory particles （RP）. Multiple activities within the RP process incoming ubiquitinated substrates for eventual degradation by the barrel-shaped CE The large size and elaborate architecture of the proteasome have made it an exceptional model for understanding mechanistic themes in macromolecular assembly. OBJECTIVE： In the present work, we highlight the most recent mechanistic insights into proteasome assembly, with particular emphasis on intrinsic and extrinsic factors regulating proteasome biogenesis. We also describe new and exciting questions arising about how proteasome assembly is regulated and deregulated in normal and diseased cells. METHODS： A comprehensive literature search using the PubMed search engine was performed, and key findings yielding mechanistic insight into proteasome assembly were included in this review. RESULTS： Key recent studies have revealed that proteasome biogenesis is dependent upon intrinsic features of the subunits themselves as well as extrinsic factors, many of which function as dedicated chaperones. CONCLUSION： Cells rely on a diverse set of mechanistic strategies to ensure the rapid, efficient, and faithful assembly of proteasomes from their cognate subunits. Importantly, physiological as well as pathological changes to proteasome assembly are emerging as exciting paradigms to alter protein degradation in vivo.
