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1.
Angew Chem Int Ed Engl ; 58(45): 16071-16076, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31469218

RESUMO

In the evolution of metal-organic frameworks (MOFs) for carbon capture, a lasting challenge is to strike a balance between high uptake capacity/selectivity and low energy cost for regeneration. Meanwhile, these man-made materials have to survive from practical demands such as stability under harsh conditions and feasibility of scale-up synthesis. Reported here is a new MOF, Zn(imPim) (aka. MAF-stu-1), with an imidazole derivative ligand, featuring binding pockets that can accommodate CO2 molecules in a fit-like-a-glove manner. Such a high degree of shape complementarity allows direct observation of the loaded CO2 in the pockets, and warrants its optimal carbon capture performances exceeding the best-performing MOFs nowadays. Coupled with the record thermal (up to 680 °C) and chemical stability, as well as rapid large-scale production, both encoded in the material design, Zn(imPim) represents a most competitive candidate to tackle the immediate problems of carbon dioxide capture.

2.
Angew Chem Int Ed Engl ; 58(30): 10209-10214, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31059186

RESUMO

Simultaneous removal of trace amounts of propyne and propadiene from propylene is an important but challenging industrial process. We report herein a class of microporous metal-organic frameworks (NKMOF-1-M) with exceptional water stability and remarkably high uptakes for both propyne and propadiene at low pressures. NKMOF-1-M separated a ternary propyne/propadiene/propylene (0.5 : 0.5 : 99.0) mixture with the highest reported selectivity for the production of polymer-grade propylene (99.996 %) at ambient temperature, as attributed to its strong binding affinity for propyne and propadiene over propylene. Moreover, we were able to visualize propyne and propadiene molecules in the single-crystal structure of NKMOF-1-M through a convenient approach under ambient conditions, which helped to precisely understand the binding sites and affinity for propyne and propadiene. These results provide important guidance on using ultramicroporous MOFs as physisorbent materials.

3.
Angew Chem Int Ed Engl ; 57(34): 10971-10975, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-29972279

RESUMO

Highly selective separation and/or purification of acetylene from various gas mixtures is a relevant and difficult challenge that currently requires costly and energy-intensive chemisorption processes. Two ultramicroporous metal-organic framework physisorbents, NKMOF-1-M (M=Cu or Ni), offer high hydrolytic stability and benchmark selectivity towards acetylene versus several gases at ambient temperature. The performance of NKMOF-1-M is attributed to their exceptional acetylene binding affinity as revealed by modelling and several experimental studies: in situ single-crystal X-ray diffraction, FTIR, and gas mixture breakthrough tests. NKMOF-1-M exhibit better low-pressure uptake than existing physisorbents and possesses the highest selectivities yet reported for C2 H2 /CO2 and C2 H2 /CH4 . The performance of NKMOF-1-M is not driven by the same mechanism as current benchmark physisorbents that rely on pore walls lined by inorganic anions.

4.
Chemphyschem ; 17(21): 3359-3364, 2016 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-27442186

RESUMO

A molecular spring formed by a hydrophobic metal-organic framework Cu2 (tebpz) (tebpz=3,3',5,5'-tetraethyl-4,4'-bipyrazolate) and water is presented. This nanoporous heterogeneous lyophobic system (HLS) has exceptional properties compared to numerous reported systems of such type in terms of stability, efficiency, and operating pressure. Mechanical and thermal energetic characteristics as well as stability of the system are discussed and compared in detail with those of other previously reported HLS.

5.
Antioxid Redox Signal ; 15(1): 1-17, 2011 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21303257

RESUMO

The Akt signaling pathway plays a key role in promoting the survival of various types of cells from stress-induced apoptosis, and different members of the Akt family display distinct physiological roles. Previous studies have shown that in response to UV irradiation, Akt2 is sensitized to counteract the induced apoptosis. However, in response to oxidative stress such as hydrogen peroxide, it remains to be elucidated what member of the Akt family would be activated to initiate the signaling cascades leading to resistance of the induced apoptosis. In the present study, we present the first evidence that knockdown of Akt1 enhances cell survival under exposure to 50 µM H(2)O(2). This survival is derived from selective upregulation and activation of Akt2 but not Akt3, which initiates 3 major signaling cascades. First, murine double minute 2 (MDM2) is hyperphosphorylated, which promotes p53 degradation and attenuates its Ser-15 phosphorylation, significantly attenuating Bcl-2 homologous antagonist killer (Bak) upregulation. Second, Akt2 activation inactivates glycogen synthase kinase 3 beta (GSK-3ß) to promote stability of myeloid leukemia cell differentiation protein 1 (MCL-1). Finally, Akt2 activation promotes phosphorylation of FOXO3A toward cytosolic export and thus downregulates Bim expression. Overexpression of Bim enhances H(2)O(2)-induced apoptosis. Together, our results demonstrate that among the Akt family members, Akt2 is an essential kinase in counteracting oxidative-stress-induced apoptosis through multiple signaling pathways.


Assuntos
Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Feminino , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Técnicas de Silenciamento de Genes , Quinase 3 da Glicogênio Sintase , Glicogênio Sintase Quinase 3 beta , Humanos , Camundongos , Gravidez , Proteínas/genética , Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-mdm2/genética , Proteínas Proto-Oncogênicas c-mdm2/metabolismo
6.
Gene Regul Syst Bio ; 4: 135-48, 2010 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-21245947

RESUMO

The protein phosphatase-2A (PP-2A), one of the major phosphatases in eukaryotes, is a heterotrimer, consisting of a scaffold A subunit, a catalytic C subunit and a regulatory B subunit. Previous studies have shown that besides regulating specific PP-2A activity, various B subunits encoded by more than 16 different genes, may have other functions. To explore the possible roles of the regulatory subunits of PP-2A in vertebrate development, we have cloned the PR55/B family regulatory subunits: ß and δ, analyzed their tissue specific and developmental expression patterns in Goldfish ( Carassius auratus). Our results revealed that the full-length cDNA for PR55/Bß consists of 1940 bp with an open reading frame of 1332 nucleotides coding for a deduced protein of 443 amino acids. The full length PR55/Bδ cDNA is 2163 bp containing an open reading frame of 1347 nucleotides encoding a deduced protein of 448 amino acids. The two isoforms of PR55/B display high levels of sequence identity with their counterparts in other species. The PR55/Bß mRNA and protein are detected in brain and heart. In contrast, the PR55/Bδ is expressed in all 9 tissues examined at both mRNA and protein levels. During development of goldfish, the mRNAs for PR55/Bß and PR55/Bδ show distinct patterns. At the protein level, PR55/Bδ is expressed at all developmental stages examined, suggesting its important role in regulating goldfish development. Expression of the PR55/Bδ anti-sense RNA leads to significant downregulation of PR55/Bδ proteins and caused severe abnormality in goldfish trunk and eye development. Together, our results suggested that PR55/Bδ plays an important role in governing normal trunk and eye formation during goldfish development.

7.
Gene Regul Syst Bio ; 3: 115-29, 2009 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-19838339

RESUMO

SG2NA is a member of the striatin protein family. In human and mouse, the SG2NA gene encodes two major protein isoforms: SG2NA alpha and SG2NA beta. The functions of these proteins, except for acting as the regulatory subunits for PP-2A, remain largely unknown. To explore the possible functions of SG2NA in lower vertebrates, we have isolated two SG2NA cDNAs from goldfish, Carassius auratus. Our results reveal that the first cDNA contains an ORF of 2118 bp encoding a deduced protein with 705 amino acids, and the second one 2148 bp coding for a deduced protein of 715 amino acids. Comparative analysis reveals that both isoforms belong to the alpha-type, and are named SG2NA alpha and SG2NA alpha(+). RT-PCR and western blot analysis reveal that the SG2NA gene is differentially expressed in 9 tissues examined. During goldfish development, while the SG2NA mRNAs remain relatively constant in the first 3 stages and then become decreased and fluctuated from gastrula to larval hatching, the SG2NA proteins are fluctuated, displaying a peak every 3 to 4 stages. Each later peak is higher than the earlier one and the protein expression level becomes maximal at hatching stage. Together, our results reveal that SG2NA may play an important role during goldfish development and also in homeostasis of most adult tissues.

8.
Sci China C Life Sci ; 52(8): 724-32, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19727590

RESUMO

It is well established that the protein serine/threonine phosphatase 2A (PP2A) plays very important roles in many different cellular processes, including cell proliferation and differentiation, gene expression, neurotransmission, apoptosis, and aging. PP2A consists of three heterogenic subunits: the scaffold subunit A, the catalytic subunit C, and the regulatory subunit B. While both the scaffold and the catalytic subunits contain only two forms, at least four families of the regulatory subunits, B, B', B'', and B''' have been identified. These regulatory subunits from different families are encoded by different genes and bear other functions besides directing the specificity of PP2A. To study the functions of the regulatory subunits of PP2A in lower vertebrates, we have cloned the full-length cDNA sequence of the gene encoding the regulatory subunit B'delta of PP2A from gold fish, Carassius auratus using 3'-RACE and 5'-RACE cloning strategies. Our results revealed that the full-length B'delta cDNA contains 2415 bp and encodes a protein of 555 amino acids. The B'delta protein displays a very high level of sequence identity with the B'delta regulatory subunit from other species of vertebrates. Regarding its expression pattern, RT-PCR revealed that the highest level of mRNA was detected in brain, a less level detected in liver, spermary, ovary, kidney and gill, and the lowest level detected in the fin. During different developmental stages of gold fish, the highest level of mRNA expression was detected at the stages of two-cell, multiple-cell, blastula and gastrula, and a decreased level of B'gamma mRNA was detected in other developmental stages. At the protein level, the highest expression level of B'delta protein was found in spermary, ovary, brain and heart, a less amount found in liver and the lowest level detected in kidney, gill and fin. Developmentally, B'delta protein was strongly expressed at the stages of two-cell, multiple-cell, blastula, gastrula, neurula, and optic vesicle, and then decreased at the stages of brain differentiation and eye pigmentation. These results suggest that B'delta appears to play a very important role during gold fish development and also in adult tissue homeostasis.


Assuntos
Carpa Dourada/genética , Proteína Fosfatase 2/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Sequência Consenso , DNA Complementar/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Carpa Dourada/crescimento & desenvolvimento , Carpa Dourada/metabolismo , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Especificidade de Órgãos , Subunidades Proteicas/genética , RNA/genética , RNA/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
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